I agree with the experience of hitch racks beating up the bikes. I really don't like any rack that holds the bikes by the top tube and allows them to swing (without taking steps to prevent swinging).

We have a "4 bike" rack and it is a BEAR getting 4 bikes on it, and they do get all beat up, swinging and bumping into each other. Two on a 3 or 4 bike rack would be OK, but you'd still have to figure out a way to keep them from swinging around and bumping each other.

They now make bars ("frame adapter") that go between the seat post and the steering tube and/or quill stem that "even out" sloping top tubes so that they hang on a hitch rack better. It is indeed difficult to get some of the smaller compact or sloping tube bikes on that sort of carrier.

I think they also make bars, very similar, but shorter to the above, that you can hook on the lower down tube or seat tube of two different bikes and keep them from swinging into each other. I would highly recommend looking into both of those accessories.

If I had it to do over again, I'd get the kind of rack that has trays that the wheels sit in so the bike is supported upright by the wheels instead of hanging from the top tube. We used a "Fiamma" bike rack of that general design when traveling in Europe several years ago, and it was very good. I don't think they sell them in the States, but they are very common in Europe. the one we had was for use with a "hatch back" type rear door (we were in a VW, but it would work with a mini van or SUV). It was nice because you could fold it and use the hatchback door w/o removing the rack. Hitch racks get in the way if you need ot open the door.