Some of the Hotels I've stayed in Central London that were lovely and all a short tube ride were
http://www.myhotels.com/my-hotel-bloomsbury/index.html
www.westburymayfair.com
http://www.guoman.com/en/hotels/united_kingdom/london/the_cumberland/index.html
If you want something cheap and cheerful though, then I alwasy find Premier Inns or Best Westerns good value for money