There are a great deal of toys you can get that can help relieve his boredom. My favorite is the buster cube. Leo will spend hours rolling it around and trying to get all the kibble out. You can also use a treat filled kong. Leo is on a diet so I only fill his with low fat goodies, but it also keeps him occupied.

I know how you feel, sometimes with my job I get bogged down and am away from home a great deal. Before I got Penny Lane as company for Leo, I used to take him to doggie daycare once a week. It was great - he would wear himself out and be a couch potato for at least 2 days. You can also see if there is a neighborhood kid that would be interested in walking him on a daily basis.

Don't feel guilty - I've found that dogs will adjust to pretty much any lifestyle as long as they are loved and cared for.