So what games have offered the best value for you hard earned cash, here are my choices

Xenoblade Chronicals-Wii

A massive game that has 100 hours plus gameplay, plenty of side quests and exploration to be done, acheivements to be unlocked and characters that require plenty of levelling up to tackle the tougher enemies the game has to offer. Im still playing this game around a year later "Bargain"

Batman Arkham City

High production values, fantastically written and brilliant cinematics, this game also offers a generous story campaign. Add this to the well thought out sidequests, riddler collectable secrets and downloadable content (catwoman levels), this was £35 well spent.

Super Mario Galaxy

Replay value galore, a game you could easily revisit for another play through, tons of levels especially going for the 120 stars to complete the game 100%. 5 years down the line and this game still gets an outing quite frequently.

Can it be a bundle? Because Steam are far and away in the lead on that one

I've only bought about 5 games full price. I am very cheap. Let's see:

Final Fantasy XIII: Pretty good value, put about 90 hours on it to get the platinum, and fairly good game in my opinion minus the linear gameplay

Final Fantasy XIII-2: Alright value, played about 50 hours or so. Not the game I was expecting though.

Demon's Souls: Definitely worth the value if you stick with it. One of my favorites this gen. I only beat it once, but got my money's worth out of it.

LittleBigPlanet 2: Didn't play this as much as I thought I would. I didn't enjoy the story mode as much as I did the first one. The online mode was vastly superior though, but I still didn't find myself playing level after level like I did the first one.

Twisted Metal: Frustrating story mode, but fun online play. Probably not worth the full price unless you are a die hard fan of the series.

I fully agree with the OP's choices and would add Portal 2 (whole package with additional co-op campaign and editor) and Dark/Demons Souls.

I tend not to buy too many games at full price, but the new Hitman game will be a day 1 purchase for me (lets hope my value for money streak continues).

Uncharted 2 I love SP & MP, played over 100 hours on Mp and still play it frequently. Bought it for £45 which s likei $70

Wow, I don't agree with quite a few of these!  But I guess that's why it differs from person to person.  

Portal 2 is one of the games I regret buying at full price.  Fantastic game, but 12 hours for the single player + co-op left me feeling disappointed.  The level editor has made me feel slightly better about my purchase, although the fact it's been constantly marked down to peanuts in the Steam sales hasn't.  I could have bought it for about £8 by the time the custom content had come out.

Uncharted 1 was very short as well.  Luckily, I didn't pay full price for it :P

As for games that are actually worth full price, not many in my own opinion.  Orange Box was worth it.  LittleBigPlanet 2 was worth it (for me) but I had a lot of interest in the level creator & custom content.  Xenoblade may well be worth full price too, haven't played it yet.  The best thing about that game is that I bought it for £10 three weeks after it came out because Gamestation seemed to be flogging all their copies for some reason.  Couldn't believe my luck.

zelda 2

Skyrim...easily worth £500 for the amount of high quality gaming content it has

Well I also got my moneys worth out of fighting games like Tekken 6 (over 85 hours )and SSF4 ( about 250 hours.)