Since the original post didn't mention anything about fishing small streams (or even streams at all!) let's not all jump to conclusions and impose our own assumptions about how we might prefer to fish a 3wt rod.
That said, 3wts can be a lot less manageable than heavier weights since they don't load as positively and they're a lot more susceptible to being buffeted around by wind when casting. Not sure at what kind of 3wt you'll be using (ultra-fast rocket launcher, smooth and slow bamboo, or something in between), the distance you'll be fishing or whether your Olympic adventures will also include lake fishing. Long-belly lines are fine since they're a bit easier to roll cast (if that's part of your plan), but then too so are double taper lines.
I've owned a bunch of 3wts including my current 8'9" Sage SP 5-piece. Unless the rod you'll be fishing is a very fast action, I'd start out with a Cortland 333 Peach DT3F. The 333s have been in continuous production for a couple decades or more for one simple reason: they're a great line at an affordable price. Why a double taper? Simple. When you're fishing a 3wt, it's not like you're gonna be banging out 80 foot casts, so the questionable advantage of a WT is offset by the DT's better roll casting and it's double line life. Sure you can buy a long belly line, but at a premium of $15 to $20 more than the 333 with little or no advantage.
If you're making the regrettable decision (IMHO) to buy an ultra-fast 3wt, then by all means overline it with the half-weight heavier WF3 Rio Grande or SA GPX. Or even a WF4F in a non-heavy design like the Cortland 333 Peach, Rio Gold or SA Mastery XPS.
My 3¢ worth.
K
