Getting a Second Rabbit

Over the past few days, I've been debating getting a second rabbit. I feel like I haven't been at home as much lately, and so I've been feeling badly that I'm not spending as much time with Walter as he's used to. When I come home at the end of the day, it's pretty clear that Walter's been lonely. I feel guilty about leaving him alone all day long, especially now that's he's calmed down so much and has become more of a snuggle bun.

I easily see the benefits to having a second bun: someone for Walter to play with and keep company. (Not to mention the fact that I found a heart-meltingly cute rabbit up for adoption online.) But what are the downsides?

Money, for one. The cost of food, veterinarian services, toys, etc would obviously double. Training a second rabbit to not chew my walls or dig my carpeting could be another nightmare. Cleaning up after two rabbits instead of just one would be more of a headache. And then there's the space factor: right now I have one large cage that wouldn't be big enough for two bunnies. Where would I house them?

Then I worry about whether or not Walter would do well with another rabbit in the house. Does he want to be Top Bun, or would he love having a new friend around? I don't know anything about bonding rabbits. If I got a second rabbit, he'd need to be around a year old. I don't think I could deal with the attitude and training issues of a bunny.

Do you have multiple rabbits? What are the benefits and drawbacks to owning more than one? Do the pros really outweigh the cons? And what's the hardest part about introducing a new bunny into the house?