I talked to machine shop today and they will most likely want to use 3/32" thick sleeves. They were also thinking about 5/64" thick ones. They showed me some diesel blocks with these thin ones and said its factory spec for Perkins for example...
I like the 3/32 if you can fit them in there. And I like to look at the entire listing of sleeves and find a sleeve with the OD I want and the smallest ID I can use so I don't machine away the sleeve to get the bore size I want.
For example, if I was doing a SBC, I'd look at the 3/32 wall sleeves in the length I want and then I pick the ID so I only take .020 or so out.
Some guys just look up the sleeve by application and I don't do that. I try and leave as much of the sleeve in there as I can.