From what I have been told, it is better to re-sleeve than continue trying to bore. I haven't done either as of yet, boring continues to reduce the thickness of the walls decreasing the strength, I have been told it can cause, if over done, piston slap. Like I stated this is what I have been told. I'm new at this also and have gotten a ton of great information from the people here at CRG!
Unless it is a block that has big value - boring past a certain point isn't worth the risk of hitting water or in the case of a daily driver, the over heating / ring seal problems that will likely come with it...
Piston slap isn't created by the boring process - its just a function usually, of poorly sizing the newly bored cylinders to the new pistons that would (should) be used in the process.
I have no experience with sleeves - but would expect that unless its a big dollar situation (read non-daily driver vehicle) that it would too cost prohibitive for most owners to do, let alone the majority of most machine / engine shops to accomplish properly and well.
For the availability of most any small (or big - for that matter) blocks, especially for situations where the vehicle isn't a collector piece requiring matching numbers - anything over a .030" bore would probably prompt me personally to look for another subject block to spend my $$'s on - especially if the goal was to use it for a long time or under severe conditions such as racing... IMHO --Randy