You can make a smaller difference in gears by changing out the front ring instead of the rear cog. If 46x16 feels too big/heavy/long I would try using a 44x16 in the front. If you're just starting out it is better to use something that feels too 'light' than too heavy and in my opinion a lot more fun to spin like mad than to lug around town. As time goes on, you'll get stronger and will probably want to push slightly bigger gears.

You might also want to start using some of the gear-charts that can be found on the internet. These charts usually have a column showing the percent step from one gear to the next. My favorite one is online here:
http://grit.homelinux.net/gi//index.php

but sheldon brown's calculator is simpler and easier to use:
http://www.sheldonbrown.com/gears/

All calculations aside, get a gear that feels right for your own legs on the terrain that you typically ride. It's less strain on your joints and muscles to ride a smaller gear, and it might be easier to do things like skids, trackstands, riding backwards, etc.