Well there is a Marriott at the top of Park Lane. So you are on the corner of Hyde Park and the end of Oxford Street. And you are on the central line to get down towards Covent Garden and further out towards Liverpool Street and the East End.
I guess it depends if you want to be near the best shops (i.e. the west end) or near the cool clubs & bars (i.e. the east end, hoxton, old street etc.
If you can find anywhere to stay in Clerkenwell you get the best of both worlds 'cos it is in the middle.
I had my wedding reception the Zetter Rooms in Clerkenwell that is nice but not cheap.
There is also the Rookery which is dripping with character but also not cheap
I think there is a Thistle Hotel in the area too which is a bit cheaper