I go down all the time & prefer San Jose del Cabo---but that's because we are old farts who don't party much anymore. We jsut sit on the beach all day-go to dinner-have a bunch of cocktails & go t obed. San Jose is very expensive..food & drink-wise. for single girls in your 20's, Cabo San Lucas is definately the spot to be. I wouldn't recommend an all-inclusive as you will want to go to various hot spots for dinner & not be stuck eating at your hotel all the time. Maybe breakfast & some lunches at the hotel but definately in to town for dinner. And try to stay as close to town as possible. Avoid the corridor or you will spend $$$ on cabs...and for sure don't get a car if you plan on drinking.
Next time check our Mazatlan or Puerto Vallarta---both more charming than Cabo I think....& just as much fun.