I don't know what "sort of hip" means and suspect that IHG doesn't either. When applied to London "central" can also mean different things to different people. The IC Park Lane is a very pleasant hotel and is well located for many of the things visitors to London are likely to want to do. For a four night stay I'd purchase Ambassador if you haven't already.

If you can be more specific about your wishes I'm sure there will be more helpful replies.