I also dug Lego Rock Raiders as a kid. Come to think of it, I don't think I've played an RTS in about 20 years:
Lego Rock Raiders
Warcraft III
Age of Empires II
The Lord of the Rings: Battle for Middle Earth (1 & 2)
Rise of Nations
Star Wars: Galactic Battlegrounds
I never got too heavily into the "strategy" part--I just loved being able to have these battles play out with catapults and horsemen and the occasional Dodge Viper with machine guns (howdoiturnthison is forever burned into my memory). I particularly enjoyed how your units could get upgrades and rank up, and they'd carry across missions in BFME so you could make them absurdly powerful. I also remember the graphics being pretty impressive to me--I spent a lot of time just zooming in on units and watching their idle animations and stuff.
I'm pretty terrible at RTS multiplayer but I love when they're in single player. Single player also lets the devs give you cool abilities and units that would be horribly broken in multiplayer.