phaolo: Ugh, mages were hard in BG2.
I felt way safer with a fighter as my main.
Did you play solo? Because I recall you get a couple of extra characters to your party right in the beginning, and at least one of them is an able fighter. So I don't think you had to play much (if any) only with your main character in BG2.
I don't recall having a problem in the start of BG2 with the same mage character I had finished the earlier BG. I played both at the hardest difficulty level.
Trilarion: Most of the time the mana regenerates automatically so I kind of would say it's an unlimited resource, except for the cases where you are trapped and have nowhere to hide and a horde of zombies/orcs/other monsters is right behind you.
I don't recall that many RPGs I've played recently where mana would regenerate constantly, only while you sleep.
In TES Arena that was quite often a problem because you couldn't sleep if there are still enemies around (ie. you have to either kill them first, or find another place to rest), and even if you did, enemies would interrupt your sleep. The only way to avoid this mostly seemed to be to find a place which was slightly elevated, then the enemies would not normally appear for some reason. Unfortunately many dungeons didn't have much of elevated spots.
In Daggerfall they seem to have lessened the frequency of interrupted sleep, so if you are able to start sleeping (no enemies nearby), then you can usually sleep until you are fully restored.
Trilarion: Anyway it would be funny if a swordfighter character would say in between slaying hundred of monsters: "Sorry, out of breath. My arms are getting weak. Need a minute to recover...".
That reminds me, in many RPGs warrior-types can also have a similar kind of "limited resource" that they have to sleep to get more of, namely fatigue. At least in Arena and Daggerfall you constantly lose your power even from mere running (let alone fighting), and sleeping will replenish it. Then again, unless you are very low level, it depletes much slower than e.g. spell points, or even health points.
In a way though, since warrior-types have to replenish their health anyway, I don't see the spell points as much of a problem. Quite often when I want to sleep in those TES games, both my health and spell points are pretty low (if for nothing else but using spell points to heal myself, at least a bit). So a warrior would have to either sleep to get more health anyway, or drink some health potions. Similarly a mage can either sleep, or drink potions, to get more spell points.