Expect lots of responses from three general groups:

Singlehanders - F16, A-cat, Hobie 16. F-16 and Hobie can take crew. F16 has a spinnaker

Doublehanders under 350 lbs - F-18 fleet.

Doublehanders over 350 - N20 fleet

It is possible to single hand the 18 and 20, but not if the wind is over about 10 kts. Minimum crew weight for F18 and N20 is around 325, so you could sail with your girlfriend or your other crew on either (you'd be slightly heavy on the F18 at 365).

Both the F18 and N20 have lots of strings to pull, which may tax your crew (if your girlfriend doesn't want to yank strings all day, put her on the tiller), but the F18 has slightly smaller sails, which may make it easier for crew to handle in heavy air.

All three groups have relatively large, well organized fleets with plenty of racing opportunity. All boats are built for speed and geared toward racing (which means they are not indestructible, and will require regular maintenance of the equipment), but can be used for recreation.

All can be found used at decent prices.

Hope it helps.