Next lens and tripod

I've gotten some great great shots with the Canon EOS 30D kit lens. Quite stunning actually , portraits of sorts that could be in a magazine. Any suggestions on the next lens I should buy thats basically sharper and a step up from the kit lens? As well as a tripod, it's quite hard to find one that can extend to 6 ft. Such a n00b but I'm learning quickly!

17-50 2.8 sigma or tamron
17-70 sigma
canon 17-50 2.8 IS

17-40 f4L

For a tripod the Bogen/Manfrotto 3021PRO is great, and gets up to 6ft.

Another vote for the 17-40L - sweet lens!

For a tripod I would say a Manfrotto 190 or 055 pro. I use the 055 pro and am 6' tall and fine it good and stable and a good working height and you can get right down low with it to for those low low shots.

Big fan of the Manfrotto 190 here. I'm also a big fan of the 17-40, however since you mentioned portraits and no other shooting interests I'll suggest the Canon 17-55 2.8 IS, Tamron 17-50 2.8, or Sigma 17-70 DC. That'll depend on preferences and budget, tell us more.

All the above lens' are great suggestions.

I've also got a 3021pro and am VERY happy with it. But, I'm not sure how it would work for a 6ft person. Probably quite well I'd reckon as mine is seldom fully extended.