Nancy: another option, if the boat you choose does not include a spinnaker & pole, is a drifter sail. AkA gennaker, aka screecher, aka Code Zero.... You'll hear a number of terms thrown around, some of them generic, some narrowly intended & proprietary.
Anyhoo, what it is: a middling-large nylon genoa that flies on its own luff. Figure somewhere between 135 and 150%, cut fat, positive luff round. In its Code Zero incarnation, the drifter is primarily meant for headings from, oh, just below a beam reach to a close reach (almost close hauled). Its purpose is to get the boat moving in less than 8kts true wind and to gin up apparent wind thereby. You can sail lower on it, tho it starts to fold up below 120* unless you have a block on the toe rail; and it's big, light, and deep-cut enuf to be really effective poled out to windward, wing-and-wing. They are inexpensive, easy to rig (generally using existing deck hardware), fairly easy to tack and jibe, and quick to douse. Also, they stuff into a tiny bag.
A drifter lacks the raw downwind power of a big-shouldered asym -- or the raw sail area of a symmetrical spinnaker, which is generally half again as big as main + working headsail. Drifter is better upwind (which matters on lakes!) than either, and somewhat easier to handle. I often run our nylon genoa (drifter) singlehand on our SJ21, on inland lakes with v. flukey winds. It's much less terrifying than a spinnaker! We can get as high as 55 degrees to the true wind (tacking thru 110*) with the drifter.
One other possibility -- tho here you start running into serious costs -- is a removable furler for an assym or drifter. Has the same ease of operation as a jib furler, without much foredeck work. To tack or jibe, you can roll up the nylon sail, change tacks, and unroll it on the other side. Presto.