IMO it depends on the amount of time and $ you are investing in marketing. If you have the time and $ to plaster the sites names all over the place I don't think the name is as important. But if you are limited in your ad budget, then yes, I think a catchy name makes all the difference.

In regards to a common word/phrase in the names, I think that may help a little with surfer recognition but more so with webmasters.

Hope this helps --Chubbs