I like Motörhead as an abstract concept and Lemmy is charming, but the music is a one trick pony after, say, three tracks. They make The Ramones and AC/DC sound eclectic and diverse in comparison.
Hawkwind I like. They are truly an eclectic mix - sort of Britain's sci-fi (early BÖC comes to mind) Grateful Dead with a bit of Blue Cheer and prog elements thrown in. And they had Stacia!
I agree that Lemmy shone more as a bassist and musician, even as a vocalist (Silver Machine) with Hawkwind than with Motörhead. With Motörhead, it's not so much his bass playing that counts (idiosyncratic as it is), but his "vocals", image and frontman role. I've seen Motörhead thrice - very early on (first gig in Germany) around 1978 (opening for a still formative Whitesnake), in the Another Perfect Day era with Brian Robertson and a couple of years ago with the current line up. It's fun for about ten minutes, but then my attention wanes and my inclination rises to plug Lemmy into an amp with less distortion. But like Rob said, Lemmy is an institution.