Sunday late lunch--upscale mexican or asian?
I am also not impressed with Salpicon, and do like Frontera quite a bit.
A few might be slightly off the path you are seeking, but I'd Consider:
Fonda Del Mar Open 4-9 on Sunday
3749 W. Fullerton
Website is http://www.fondaonfullerton.com/
Sol de Mexico (You might REALLY like this one
)3018 N Cicero Ave
Chicago, IL 60641
Not sure how far north you'd like to go, BUT:
La Casa de Isaac
431 Temple Ave
Highland Park, IL 60035
Also, Adobo Grill:
3382 N. Milwaukee
Tepatulco might be the best option depending on what time you're looking for. They close between lunch and dinner - check for times.
2558 N. Halsted
For Thai, I'd do Tac Quick. Sheridan and Irving. My top Thai place in the city, but that's my opinion. I love this joint.
3930 N Sheridan Rd
Chicago, IL 60613
Is Indian up your alley? If you don't need a fancy atmosphere, I'd be at Khan's BBQ on Devon in a heartbeat. Tiffin for a somewhat fancier atmosphere.