I've not caught the bug... yet.
At this point the classic line "it was this big" says it all for me. If the fish is about arms wide from tip to tail, it's probably the limit of the size I like to tackle on fly. Steelhead, salmon, tarpon, bones, stripers, mahi mahi, roosters, searun trout, you get the gist.
Now obviously it's a personal preference thing - I would rather not work really hard to land a fish where some people see the extra effort as the fun part.
But in this size range there's plenty of challenge too - I've had my clock cleaned many times by big steelhead on stout gear. Tarpon - just expect to break something. Bones 5lb+ are a nice challenge but those double digit bones are about at the limit of an 8wt's capabilities and a 7wt is really outgunned by such a fish. Stripers frequently bring me deep into the backing and a 9wt is barely enough for cow bass handling, bent to the cork.
But who knows what will happen in 2009