I have only been playing for a while, but it appears to me that there is no way to enter live mode without an active quest. Is that true? Some of the posts on here seemed to suggest otherwise, but I might just have misread. I'd appreciate if someone could shed some light on this

If you open the cheat window and enter "showallquests", you should see "Free Time" under there. This is the "quest" you want.

The Free Time quest is intended to let you play Sims without having to quest, or deal with responsibilities, and lets you switch between Sims as well. This is the only way to enter live mode without a proper quest.

From what I understand, (I haven't made it to the end yet), once you run out of QP you have finished this kingdom and it unlocks the free quest. Now if you have enabled the cheat command, how-to here, you can Ctrl + Shift + C and type in "ShowAllQuests" (w/out the quotes) when you're on the kingdom page. Then next time you pull up your quests, you should see ALL the available quests, just choose the free quest (or freetime - can't remember! ). I've seen this, but I haven't done it yet!
ENJOY!

Ha!Ha!Ha!
We most have been typing at the same time!!! LOL :D

Yeah, that happens a lot on message boards!

I've actually done the Free Time quest, so I can vouch that the cheat definitely works. I'm doing it in between going on quests, actually, although it's designed to be played at the end of your quests/ambition, as jbeach says.