We carry bikes one of two ways, depending on how far we're going, how much stuff we have, and how filthy the bikes are. I have an Outback and DH has a Legacy, and both are wagons.

If it's a long trip and we have lots of stuff, the bikes go on the roof to make room for baggage and Dog. If the bikes are filthy, they go on the roof. If we're not carrying much gear and no Dog, they go inside the Outback on a fork-mount rack that DH made from scrap lumber and some of those $20 fork-mount thingies for pickup trucks. It means removing seatposts, but a line with a marker make re-installing to the perfect height easy. Carrying them inside definitely helps the gas mileage compared to the roof rack.

I'm 5'4, and can put any of my bikes on the roof, including the full-suspension beast.