I normally use the Sheraton Park Lane when in that area, though I have tried Le Meridien now it's in the SPG fold. Had one very good experience there (as the Sheeep's do goers from June can attest!) and one dire one where I was stuffed in a tired room at the back.

Though I hate to mention HILTON, there are some cheap-ish deals in the Park Lane one and it has been refurbished recently.