FS, Bucc, Rhodes
....In that order. At least in my humble point of view.
Of the three designs the Flying Scot is likely the best choice. Reasonably quick, very stable and forgiving, and comfortable. You can rent one at Belle Haven Marina Alexandria VA to see what they are all about. Be careful when shopping for these as the hulls are cored and may be wet/delaminating. They tend to hold their value well though due to their popularity..
The 18' Buccaneer is essentially an oversized Laser II. The low freeboard and tenderness means you need to pay attention lest you want to be swimming in sometimes filthy Potomac/Chesapeake water. Thee is a small but growing fleet in S. Maryland and you may be able to try one out there.
The Rhodes 18, as mentioned before, is heavily laid up and will takes many years of abuse. But because of its weight you'll find the performance very sedate and, in in the light summer winds common to the Potomac and Chesapeake, you may be disappointed. These boats are popular in New England and, specifically, Cape Cod Shipbuilding's home waters of Buzzards Bay -- where 12 knots of wind or more is not uncommon. And yes, the cockpit can feel cramped (unless you were raised sailing a Mercury).