Government Man's Guide to San Diego Hotels 
(tiny edit)
Part IV: Hotels Near Trolley Stops, Downtown to Lemon Grove
Well, taking the Blue Line north didn't work out so well, so let's try taking the Orange Line east. Unfortunately, most of these stations are for residential areas with no hotels. You have to go all the way to La Mesa to find anything.
Orange Line Stations (La Mesa)
La Mesa Blvd Station
The fare to the Convention Center is $2.50.
38. Ramada Ltd La Mesa CA (0.43 mi) *.5
$114 7911 University Avenue, La Mesa 91941