I am a newbie at this, so forgive me if this subject has come up before. I have been shopping for a new bike after being off of one for 20+ years. I am 300+ and 6'-4". I have been shopping in the Philly area for a comfort bike and my LBS have suggested the Giant Sedona, the Trek Navagator, and the Raleigh SC 30. All of these bikes have front suspensions, aluminum frames, shimano deraileurs, and seat suspensions. Is there a difference between them? The prices vary from $300 (Giant) to about $350 (Trek & Raleigh). Weight is a concern of mine, but after looking over the other posts, it is less of one. These bikes all look the same to me, so any help would be greatly appreciated.