As far as the trees go, you can get these plastic sleeves at gardening stores that just wrap around your trees. The deer can't (or won't) chew through these. They're really inexpensive and, since they are brown, aren't an eyesore.

I know it may sound old fashioned, but a scarecrow is, in many cases, enough to get rid of deer. If that idea isn't too appealing, you can buy scare tape. Any bright colored tape will work. Just put it in random places around your yard. Change the location of the tape every couple of days to prevent the deer becoming accustomed to it. This should work, and is a very cheap way to solve the problem.

Hope these help you out!

set up heavy duty sprinklers, spook them away with water shooting at them.

Have you considered buying a shotgun?

I would recommend regularly hiding blocks of salt in your neighbors' yards. While there may be more deer in the vicinity, they, hopefully, wouldn't be in your yard.