How do you guys transition your playing time?

For me I went something like this (was born in 1987):

                               Main System          Also Owned & Playing

1992 - 1995        Sega Genesis

1996                     Nintendo 64        Game Boy, Genesis 

1997- 1998         Nintendo 64        Game Boy

1999-2000          Nintendo 64         Game Boy Color, Dreamcast

2001                    GBC                         Nintendo 64, Dreamcast, Gamecube

2002-2003         Gamecube             Dreamcast, GBC, GBA

2004                   Gamecube              GBA, DS

2005                    DS                             GC, GBA

2006                   Wii                             DS, GBA, GC

2007 - 2010       Wii                             DS

Basically:

1992-1996 = Genesis (age 5-9)

1996-2001 = N64 (age 9-14)

GB/GBC 1996-2002 (age 9-15)

DC 1999 - 2001 (age 12-14)

GC 2001 - 2006 (age 14-19)

GBA 2002 -2006 (age 15-19)

DS 2004- ??, (age 17- ??)

Wii  2006 - ??, (age 19 - ??)

Will probably continue using DS into 2011 and Wii into at least 2012. Looking back, when I have more than two systems I use at once I don't get to buy as many game as I want, so I'll probably hold off on 3DS until I'm done DS...which will be a while given my backlog.

Of the systems I've owned I'd probably go something like this for personal enjoyment:

Wii > DS > N64 > GC > DC > Genesis > GBA > GB , based on time used / games purchased.

Hrm... this is kinda tough. I'm just going to mention when a system came into prominence for my playing; this does not mean that I stopped playing the other systems. (Yes, I've used my NES some this year!) Any skipped years mean that my main system was not changed from the prior year(s).

1983: Atari 2600 (Yes, I started gaming that young. I remember being angry at a friend turning off the system because my game was going "too long"- defined as 15,000 points with 1 ghost in Jr. Pac Man.)

1987: NES

1990: Game Boy

1991: NES (again)

1992: SNES

1995: Game Boy, through the SNES adaptor. So which does that count as?

1996: SNES

1997: N64

1998: PS1 (Yeah, the 64 wasn't getting my RPGs; Quest 64 just didn't cut it.)

2002: GBA (I was about done with home consoles...)

2004: No dominent system. (I was losing interest in gaming by this point.)

2006: DS (This was my make-or-break system for gaming... you see where I am now...)

2008: PS2 (One word: Atlus. Though this would transfer...)

2009: DS (Yep, more Atlus. And this is by far my most used system for this year.)

Systems owned not mentioned: GBC, Gamecube, Wii, Genesis, Saturn, Dreamcast, PSP, XBox, 360, Atari XE, FDS. Though out of fairness, some of these were gotten late or post-cycle.

For me it'd be hard to break it down in the first mannor, I've always had lots of consoles and I tend to play most of them on a semi-regular basis, but I'll give it a try based on years.

1988-1992 ~ NES only (ages 3-7)
1992-1994 ~ SNES, Gameboy, NES (ages 7-9)
1994-1998 ~ SNES, Genesis (ages 9-13)
1998-1999 ~ SNES, Playstation, Genesis (ages 13-14)
1999-2002 ~ Playstation, N64, Gameboy Color, SNES, Genesis (ages 14-17)
2003-2004 ~ Playstation 2, Gamecube, Playstation, Gameboy Color, Dreamcast (ages 18-19)
2004-2005 ~ Playstation 2, Playstation, Gamecube, GBA SP, Dreamcast, Genesis (ages 19-20)
2005-2008 ~ Playstation 2, Playstation, PSP, Gamecube, SNES, GBA SP, Dreamcast, N64,  Genesis (ages 20-23)
2009-2010 ~ PSP, Playstation 2, Playstation, SNES, Sega CD, Dreamcast, Gamecube, Saturn, N64 (ages 24-25)

As for systems owned in order of total enjoyment...
Playstation > SNES > Playstation 2 > PSP > Gamecube > Dreamcast > Sega CD > Genesis > NES > Gamecube > Saturn > GBA SP > N64 > GB Color > GB

This is a rough estimate, but here's the ballpark of what I've been playing (these are just the times I regularly played these consoles, doesn't consider the times I'll still occasionally pick them up):

1989 - 1995 NES,  (3 - 9 years old) - I still played Mario 3 and Bubble Bobble well into the life of the Super NES

1989 - 1993 Atari 2600 (3 - 7 years old)

1992 - 1998 Super NES (6 - 12 years old)

1996 - 2002 N64 (10 - 16 years old)

2001 - 2004 Gamecube ( 15 - 18 years old)

2002 - 2005 Dreamcast (16 - 19 years old)

1991 - 2004 Gameboy/GBC/GBA

late 90s, 98-99? Gamegear

2005 - 2009 DS, though I will probably pick it up again soon once I get DQIX and Pokemon Black/White

2005 - present Xbox 360 (19 - 23 years old)

2006 - present Wii (20 - 23 years old)

well I have been playing game since i remember. About the age 3.

Ninteno entertainment system. Master System. Magerdrive. Super Nintendo Entertainment system. Gamegear gameboy.

All these were in my house ever since i can remember. I was born in 1991.

NES. never really played it. Last time i remember using it was 1996.

MasterSystem. NA-2010. I played it on and off up until about 2000.

Gamegear. Na-1997 I loved it but then it broke. i didnt play it that often though but more then NES and MS

Megerdrive. NA-2010. I love this console to death. Still play it on a regz to this day.

SNES. NA-2010. I played this console a but when i was younger. I play it now and again just for a few classics.

gameboy.  Never liked it. Always playing my gamegear. it was in my house but i never used it really.

PS1. 1996-7-2000.  This is the console that taken over the place my megadrive once had. Played it to death

N64 1998-2010. Never really played it that much. Still play it now for the classics i loved so many years ago.

Dreamcast. 1999-2002. Never really played it. Just like a few games on it.

PS2. 2000-2010. Loved this console. Played it all the time. Still play it sometimes.

Gamecube. 2002-2010. Hated this console. Like a few games on it. never really play it. But still gets some use.

x-box. 2003-2008. Hated it. Only played a few games. Dont use it anymore

PSP. 2005-2010. Love it. Still use it.

X360. 2005-2010. Thought it was ok. Didnt really use it once i got the PS3. still play 1 or 2 exclusive

PS3. 2007-2010. Love this console. Play it all the time.

Most played system has to be the PS2 because once that came out i never touched me PS1 again cause the PS2 played PS1 games.

1995-199something- Game Boy..................7 y/o

Mid 90's-late 90's- Mega Drive....................7

1998-2002- PlayStation............................10

1999-2001- Dreamcast.............................11

2001-2005- Game Boy Advance/SP later.......13

2001-2007- PlayStation 2.........................13

2005-now- DS......................................17

2007- now- Xbox 360/now Elite................18

2007- now- PlayStation 3/now 250GB.........19

2008- now- PSP....................................19

2010-onwards- Wii................................21

A bit of MS and Sega. A lot of Nintendo & Sony.

1987-1991: NES (also had Atari 2600, Game Boy in 1989)

1991-1995: SNES/Genesis (also used Game Boy, Sega Gamegear)

1995-1999: Sega Saturn/PSX (from 1997)

1999-current: PC

2002-2006: PS2 (also had Dreamcast, GBA/GBA SP)

2007-current: Xbox 360/Wii (also DS Lite/XL, PS2, PSP and PS3)

Date start, Date no longer own, System

1996-2007: NES (Grandpa's House)

1998-?: N64

1998-2002: GB

2002-2004: GBA

2004-2006: GC

2004- ?: DS (various versions)

2006 - ?: Wii

2009-2009: PS3

2010 - ?: Xbox 360

Enjoyment? Wii>Gamecube>Nintendo 64>Nintendo DS>NES>GBA>GB>PS3>360

N.B PC kind of there all the time

I have so many consoles, plus Ive always gamed on PC, that I couldn't break it down so cleanly.