I use a variety of different themes, depending on the site. Pagelines is OK though Platform is better, IMHO, and is one of the few that has a top widget area you can use for ads... since that's the prime position for clicks, it's pretty important!
Other than that, I use Magazine Basic on several sites, with customised CSS to make it slightly less old and wrinkly. It's basic but it has most of the essentials and doesn't waste time with sliders and other bizarre stuff that just uses space without giving any kind of benefit.
I really like the look of Montezuma as well but it's a total cow to adjust in any way so I only use it on a couple of sites. It's VERY white, too, which sucks... but it's so difficult to tweak... bah.
I have a couple of more graphical sites based on the Pinblack/Pinblue theme (again with changes). The thing with those is that the monetisation is VERY limited: there's no sidebar on the main page and only one on the single posts. That said, it looks nice so people tend to stick around a bit longer and, with galleries, they often arrive direct to a page from their search, so there's no major loss.
Other than that, I also have individual sites working on odd themes: one on Silver Orchid (which I absolutely love for magazine-style sites, even though it's a bit buggy), a couple on old StudioPress layouts (retro!), one on Themolio, one on QuikGallery and even one on QuickPic.
I find that monetisation relies less on the specific theme you choose than on the way the chosen theme suits the site.
