Depends what you want to do. 20 CHA I believe is enough to get you infinite money as you can sell items back to shops for more than what you paid for them. Not that you'll need it, but breaking the game can be fun in its own right.
IIRC there are a couple options around 18 or so, but they're rare (I think mainly with Ravel).
On an unrelated note, does anyone ever feel like BG2 maybe "borrowed" a bit from PS:T structurally?
1. Wake up in a mini-dungeon with no idea what's going on. Escape.
2. Wander around a large city completing side quests, gathering companions, and trying to find out what's going on
3. Find out where you need to go next and run errands around the city to make it happen
4. Exposition and confrontation with a powerful spellcaster after making your way through a brief maze
5. Travel through some outer regions trying to both gather more info and try to find your way back
6. Return to the large city to wrap up any side quests and try to make a way to the final confrontation
7. The Final Confrontation
Not saying that BG2 was a blind rip-off of PS:T, because, I mean, the games are very different. I've just always thought it was an interesting parallel.
Not so sure about those aspects. I's really just expanding the most popular part of BG at the time, i.e. the city, and shifting it earlier in the game - these days, fans of BG1 like it for the open exploration that was later dropped from most party-based crpgs, but at the time the general consensus was that the game picked up tremendously once you reach the city, and there was criticism of Bioware for holding back that aspect of the game until several chapters in.
I do think PS:T had a massive influence upon the more prominent use of story and voice-acting in BG2, and the generally darker tone compared to BG1. The expanded companions, with Imoen becoming central to the main quest, appears directly influenced by PS:T.
It's also the only time that Bioware has tried to subvert genre expectations instead of strictly following them. It takes the 'chosen one on an inevitable path to defeat/replace the big bad' from BG1 and countless others, and replaces it with a 'completely unrelated outsider jacks the destinies of both the chosen one and the big bad, for his own personal, and comparatively trivial ends (personal revenge on a single city v GOD OF DEATH)'. It also takes the usual 'villain sits in the end dungeon waiting for the hero to come and defeat him', and gives a pair of villains who fight the player 7 times between them over the course of the game, getting stronger and accomplishing goals as the player does. Whilst there isn't the same constant villain interaction in PS:T, I think the general idea of doing something which upends genre expectations was inspired by it, it's a very non-Bioware approach.
I'm guessing that development of the maps and structure for BG2 would have been at an advanced stage before PS:T was released, but the story and voice-acting was the last thing to go in back then. Developers would build a game and systems, and then add the story/campaign once the rest was in place (hence the popularity of expansion packs, cheaply creating a full campaign using existing systems). They would have had time to rethink that aspect upon seeing PS:T, with minimal perceived risk (story just wasn't that big a focus before BG2).
