Personally, the 24L is ideal. (Note, I own both the 24L and the 34L). I am 6' 3", and it works great on hills, slopes, uneven ground, etc etc.
If you are going to be shooting on sandy or soft surfaces (moss, grass etc), then I recommend the spikes.
If you are going to be shooting on rocks, ice, or slippery surfaces, then I highly recommend the Rock Claws.
I just returned from 2 weeks in iceland (funnily enough, with Josh Holko, plus Andy Bigs and Daniel Bergman), and a considerable number of tripods on the trip were RRS 24L's, and some 34's along with the usual collection of either BH 55's and a few Arca-Cubes.
I actually got the 24L for my wife, and decided I liked it better for the field over the 34. It is pretty much just as strong, stable etc. Certainly survived iceland in winter just fine. (Needed to be cleaned once after the black beach. Sand got in the threads). Fully extended it is only about 3" shorter than the 34. Still taller than I am.
Either of them definitely seem to be the landscape photographers tripod of choice.