I have had contenders before but in rifle style. I have a frame and a 14 inch barrel in .223...

Whats a good scope or sight that works well? Any tips or tricks?

I have this on my Encore pistol (15") in 250 Savage and I think the glass is great. The longest shot I have made to date is 167 yds on a whitetail deer.
I don't know of any tips or tricks........just depends on what you use it for.

Nikon Force XR EER Pistol Scope 2.5-8x 28mm BDC Reticle

Mjbgalt: My Thompson Contender in 223 Remington has a Burris 3x9 pistol scope on it.
At the range it works rather well and I have shot many great groups with this pistol - I credit the quality manufacture of it, the amazing trigger, my ability to sand bag the heck out of the gun and top quality handloads.
Afield after Varmints and Coyotes the 3x9 Burris (and most every other pistol scoped pistol I have shot!) does not work so well!
The field of view is small and the eye relief is critical - but I have made do and collected many Rock Chucks, some Prairie Dogs, a couple of Badgers and a Coyote with this rig.
My Contender is also the 14" heavy barrel and again I am impressed to the max with its accuracy - it is just slow/difficult afield to use on Varmints - I do it, but its not easy to do.
Hold into the wind
VarmintGuy

I would advise to look at some of the new pistol scopes like weaver, burris, etc. I feel like the newer ones have more generous eye relief to me. I've taken a few of my contender pistols hog hunting and I am big fan of red dots opposed to scopes in the blind/stands/walking around at night. That being said, what will you want to do with the 223? Plink, Hunt, jack of all trades? I feel like it would be hard to go wrong with 2-7 pistol scope.

The idea is a 223 for practice and varmints and then 357 max for deer. I think that combo should fill all my needs. I live in Ohio so I cant use anything but straight wall cartridges for deer

Hows your search coming along with the scope? decided on anything

No. Not sure yet. Might just use a red dot on the 357

I put a Bushnell 3200 Elite on my Encore handgun. It has worked quite well. Granted, not made anymore so would have to search for used.

The Bushnell 3200 & 4200 lines of scopes were way better than their price point.