I spent about a month in Bolivia in 1997, most of it spent trekking but also climbing HP on borrowed gear. It's not particularly dangerous or technical, but it's still legitimate in height and not as crowded as others often say (at least when I climbed it). Seeing the Gran Poder festival (think 48 hours of Aymaran Mardi Gras) in La Paz was amazing, but I agree w/ the others that getting out of sight of La Paz is a good idea. I spent several days in Sorata and another 8 treking around the Illampu Circuit. Ancohuma and Illampu are gorgeous peaks that have reasonable access from Sorata. Our trek took us past the Laguna Glacial which is not very hard to get to or find. Sorata itself is a nice town w/ good food available from the local farmers' market and guides and porters available at the Residential Sorata if you need them. The Residential's owner is a nice German guy who will keep your stuff locked up while climbing. The other bonuses of staying at the Residential are the floral garden, ancient iron spring beds and an old TV and VCR that get set up for movie night once a week, playing movies as selected by the audience. The copy of Butch Casidy and the Sundance Kid has an annoying hum in the background, but there's no better setting to watch it in the world. We visited the town at a time of crisis, when the owner of the other hotel in town was arrested for hiring youths to throw stones down onto campsites of trekkers working w/ rival guides hired from the residencial. He was busted after hiring a kid to throw stones on his uncle's group. The same guy was also apparently trying to break up the guides' union they had been forming. Anyways, the guides who were the best in town were 2 Germans. The one named Peter can regularly be found, beer in hand and barefoot, most mornings at the Residencial. He seems a little crazy but knows the most about the mountains and has taught most of the local guides all they know about steep ice. If he's still alive and coherent, he's probably worth a talk. The other guide had recently written a book pointing the finger at the local bad guy and was considering getting out of town before his head got split open. If you're going on a trek, it's probably worth hiring a guide, as the trails are tough to follow and they help in talking bandits out of robbing you, as happened to a group of Isrealis we met coming into town...
I guess I didn't include as much true beta in this message. I hope it gives you a little flavor for the country, although I can't really do it justice. It is truely a mountaineer's paradise, but when you're there, don't just peak bag, drink a little mate (ma-tay) and take a look around.
Incidently, I'm going back in June as well. I'm flying down on June 12th and am hooking up w/ some others on the 22nd or 23rd w/ nothing planned for the time in between. If anyone has room left on their rope, I'd love to get a climb or 2 in before my friends show up.