Hyatt on Loisiana Street is decent. there is also the Doubletree at Allen Center. Best hotel is considered to be the Four Seasons, but I don't know if they offer miles. Also you could add an extra 1000 miles by flying to EFD through IAH if you want to spend the time. EFD and IAH should be about same distance from downtown. Lastly there is an AA flight nonstop from LGA to Hobby if you want to save time and fly AA. Hobby is also closest to downtown.