Actually, I think it's getting late. I prefer to plant roses in the very early spring (as the snow is melting) and in the autumn after it has started to rain again. You can, however, plant roses even in the heat and dry of midsummer, if you give them a little shade (with a shade cloth, a deck chair or something) and a lot of water for the first few weeks after planting.

For variety, you can check out Pickering Roses and/or Heirloom Roses. They both sell online and provide both very high quality plants and good service. Heirloom also has an exceptionally lovely print catalog.

Stadlers in Olney (though pricey) are likely to have a good selection of just about anything. Or the Dutch Plant Farm in Frederick. In Carroll County you're possibly a zone colder than Leslie, so it's probably still good season for planting.