Unfortunately, most of my favorite places probably wouldn't appeal to someone looking for a "basic" menu.
Seviche is IMO the best restaurant in town. Either location. The one on Bardstown Road has the best surroundings and ambiance. Definitely NOT basic, but amazing.
Cafe Lou Lou is another favorite of mine, but might not fit your criteria.
Jack Fry's would probably be more to your liking and is outstanding.
Z's Oyster Bar & Steakhouse has great steaks, and Jeff Ruby's downtown is high on the glitz and glamour scale. Both have pretty simple food. Steaks, seafood and sides.
Rivue and Ruth's Chris have average-ish food, but can't be beat for a romantic sunset view, as both are high atop buildings.
L&N is great, especially if you are a wine lover.
Corbett's may be the most sophisticated restaurant in town. La Relais is both romantic and very, very good. I can't describe either as "basic" though.
Primo is great, as is Proof. The Oakroom has traditionally been excellent, but they are undergoing some staff changes so I don't know how it is holding up. Again, not really "basic".
If you like traditional Italian home cooking (red sauce), don't miss Melillo's. Another favorite of mine.
Toast is a great place to grab breakfast/brunch one morning.
I guess given your specifications I would have to recommend Jack Fry's as a good choice. I'm sure you could find something you'd like at L&N, or Primo also. Melillo's for italian. Besides than the steak houses, the others might be a little challenging for someone looking for "basic" flavors. Not that you wouldn't find something you would enjoy at any of them, but your options might be a little limited.
A bit more specificity with what "basic" means and what part of town / price range you are looking would be helpful, but I would recommend reading Robin's reviews of the places I listed and deciding from there. Many have menu's available online also.
I only ask one favour. Please try not to eat at any of the mass chains in town. We have too many unique local places to mess with those. Ruth's Chris and Jeff Ruby's are technically chains, but they do have unique atmosphere or location things going for them that helps make up for other shortcomings.
Footnote : I left a lot of great restaurants out of my list, but you only have a weekend, so...
Enjoy your stay and your eating!!