Yes, great idea! Bunnies love to go exploring and they like to be up high where they can see everything, so adding a couple of ramps and shelves would be a great idea.

I believe the House Rabbit Society says the minimum size of a rabbit cage should be no smaller than 4 lengths of your bunny when he is laying flat to the floor with his legs extended out behind him.....you measure from the tip of his nose to the very end of the extended leg. This posture, by the way, is an indication of absolute trust that your bunny has in you. The unused closet/no doors sounds absolutely perfect.

I have several holland lops. They have a very sweet disposition and are usually relaxed. If you get a baby bunny (doesn't matter what kind), know they will be hyper and get in to every kind of mischief you can think of. They are also impossible to litter train. For significant health reasons, all bunnies regardless of the sex, should be spayed or neutered at 4 months of age by a rabbit-specialist vet. Rabbits are prone to develop reproductive cancers. Also once a rabbit is spayed/neutered, they calm down some and their urine is less strong (no longer trying to attract a mate). Bunnies are also very social animals and will demand a lot of attention. I don't want to start anything but it is always better to have 2 rabbits so they can keep each other company when you are not at home. Oh one last thing, lops, because of their floppy ears, need to have their ears check about ev 2 months and cleaned when they have excess ear wax....if it is not removed the rabbit stands a chance to develop an ear infection.

Well, I've gotten WAY off the subject! Good luck in finding a rabbit. They make great pets and I'm sure you will be happy with one.