I tend to like a fence as part of the deal as well. However, until we come up with a way for a temporary labor force to come and go we will continue to have a problem. The problem we have now is temporary, or seasonal, workers bring families and stay. Once they get a foothold they provide the access point for friends and relatives back home.
Until the employment issue is dealt with the magnet drawing these workers will be strong enough for them to overcome just about any barrier.
The more I think about it, a fence is not a good idea. The fence will get built and the politicians will say they fixed the problem and everything will continue as it has for the last 30 years. Until Congress and the President are committed to enforcing the immigration laws, a fence is just a waste of chain link and cement.