Hiya,
Kasbah is a good place to be heading although what u will find is that the drinks can be a bit expensive in some of the places, esp chinawhites, maskos and cream. The Irish Centre is also a good place to head, and u will find it can be a bit cheaper than Kasbah. The Yumbo centre is good for a laugh(and if u wanna see a good drag show) but very expensive. Also u have bars on the beach front including Linekers Beach Bar that could be worth a visit.
Clubwise, if u wanna go to more reasonably priced places, Fiddlers in the irish centre and The Point seem to attract alot of people.
What time of the year are you going and which Tour Company are you travelling with? If you're on a package deal with mytravel, thomas cook,first choice or thomson it might be worth ur while booking stuff with ur rep. I know alot of people think they're a rip off, but they can be value for money. Things like the booze cruise, school disco,foam party etc that include free bar can actually save u money.
If you want anymore help just let me know.