I bought 3 domains from 1&1, within months I transferred away... hideous! I can't think of a single good word to say about them. Cheap and very nasty (and you can quote me).

I use a number of hosting providers. But the one I like for dotnetnuke is http://www.re-invent.com. They pretty much have it all sorted. Only thing they don't have is a control panel for IIS (ideal for restarting sites) or SQL server (detaching/reattaching databases). They also don't have a phone support, at least on their basic packages (and really, you don't need it). However their email their support is rapid, organised and fast. They are based in the US (I'm based in the UK). A lot of people use go-daddy, but I avoid because they have their servers on medium trust. Also avoid m6.net like the plague. On the whole I believe you get what you pay for. 1&1 being cheap as chips proves the concept.

Others may have other ideas, I generally stick with re-invent.com for dotnetnuke as I see no reason to move. If you go, tell them I recommended you and I therefore deserve 100% discount for the next five years :).

Cheers...