You could buy another Trek 4300 for $420.00. The Trek 7.3 FX is a good hybrid and you can find last years models going for $420.00 (msrp=$530.00). If you are going to use it on the road more, this is the bike I would get or something similar from other manufacturers/brands. You'll appreciate the speed difference with the 700c tires. I'm only listing a few Trek bikes since that's what you are familiar with. There are a lot of options in your price range. You have to do some research and take a few test rides with the bikes that interest you.