So lets say my lady and I, are working on a game. She decides she wants to get further in the game and I'm gaming it out on the one. Can we both be on Xbox Live with the same account, at the same time?

Yes

I have two Xbox 360s. I'm afraid to even try to log in on both of them at the same time. jlmurph2 says yes so I'm gonna assume he knows what he's talking about.

You cant log in 2 Xbox 360's but you can definitely log in an Xbox One and Xbox 360 at the same time.

I know this because my liverroom xbox has been turned on by accident before and I was logged off in the middle of a game.  So I made sure to set the liveroom xbox to not log me in upon start up.

Taken from IGN's 'ask microsoft anything about Xbox One' article.

If I sign in to Xbox Live on my Xbox One, will I also be able to sign in on the same account on my 360 at the same time? Say someone is using the Xbox One in the living room and I'm playing my 360 in my bedroom. Will I be able to use the same account?

WHITTEN: Yes this works! You’ll be able to be signed on with the same gamertag on both an Xbox 360 and an Xbox One console at the same time. However, like today, you can only be signed into one Xbox 360 and one Xbox One at a time.

So I guess you can't both be playing at the same time? I don't know, it's a confusing answer. 

Lol confusing indeed. Read it three times and was confused three times

My take from it is that you can have your account signed onto both consoles without having to recover it on either but you can't be playing games on both online at the same time? idk.

No, it says that you can play on the Xbox One and Xbox 360 at the same time but you can't log into two of the same consoles.

Xbox 360 + Xbox One=Yes

Xbox 360 + Xbox 360 = No

Xbox One + Xbox One = No

Also

Wii U + Xbox One = ?

No, hes's saying you can't play more than one 360 at a time or more than one X1 at a time. 360 and X1 can both be online playing whatever.