Actually, regular GC & Wii games probably aren't lagging on the TV - I played around in Super Monkey Ball and Mario Kart Wii for a little while and they didn't feel sluggish after all. It's harder to measure without a comparison available that I can be certain isn't affected by lag, but I think regular GC & Wii is fine.
I did some research into the Wii GX emulators. There are conflicting reports about whether the emulator itself introduces lag, but someone did a detailed test comparison between Super Mario World on a SNES, through Virtual Console, and through a few different settings of snes9x GX. spreadsheets.google.com/pub?key=0Am1TqCvtDeiQdE9DbW9wSnN5ZTdsNW9YZEhZZkFhVlE&hl=en&single=true&gid=0&output=html
- these were the findings. So you're likely right that Wii emulators are introducing lag on their own (a bummer for my hopes to practice using those emulators...). I tested Super Mario 64 Virtual Console earlier as well and compared it to how it felt on N64, and I could not perceive a difference.
I'm still concerned about GB Player, though. Most of the testimonials I've read regarding it say that it doesn't lag with the correct setup/TV. Comparing to a GBA SP, though, there is definitely noticeable lag on this Samsung. Recording GB games is what I'm primarily interested in regarding the GC, so this TV doesn't seem to work after all.
By the way, I am indeed using a Wavebird, but I've never noticed any lag ever while using one so I don't think it would be the cause of the problem. I also tested the same things with a SNES -> GC Retroport, which I've not seen anyone say lags, and there was no change in results, so I don't think controllers is the issue.
Anyway, it turns out the TV has some sort of sound issue as well, so I'm going to get rid of it anyway. Does a TV like, say, this one - newyork.craigslist.org/mnh/ele/2739785217.html
- look like it will have no problems with lag? I have a feeling now that flatscreen sets are probably less reliable that roundscreen ones... However, like Ahab said, if anyone has any recommendations for a CRT set or type of set that should absolutely not have any kind of lag, I would very much appreciate it!