I have to join the group heaping contempt upon the Complete Warrior Samurai Class. It really is very limiting compared to other versions I have seen. And after playing "real"

Rokugani Samurai in the L5R rulebooks, it really doesn't add up. If you have access to the Oriental Adventures sourcebook, I would use that (it is superior). There is an update of OA to 3.5 D&D in Dragon #318.
Swashbuckler? Well, they aren't exactly a powerhouse. I'm always partial to lightly armoured, agile types, but it hasn't always played out the best. As stated by others, most people I know have tended to dip into this class for 2-5 levels, then change to something else, like rogue, scout, or ranger. One friend made a Li Mu Bi clone with Monk and Swashbuckler levels. A while back there was a Campaign Components article disussion a swashbuckling campaign, with some excellent Parrying rules, that dovetail nicely with this class. (In Dragon #301)
Hexblades have great flavour and have some solid mechanics behind them. Again, they don't have the raw power of a fighter or barbarian. Their spell list has a particular(and suitable) flavour, too. If you want more leeway with spells, it is probably better to multiclass fighter and sorcerer/ wizard, then go spellsword. I'm going to use Hexblades amongst the island cultures in my new campaign, representing their hatred of outsiders (there won't be alignment, just affiliations).
A recent Dragon magazine(Issue #339) gave some more options for Hexblade curses, and Hexblade feats.