That's quite a few suggestions, thanks everyone!
- Jetpack - Not solid enough to be used as the main system. I would have to carry it around with me, it requires manual charging after every few minutes of use and it could be lost. I might store one at the entrance as a backup but that's it.
- Steve's Carts Elevator - Will have to look into it, I have no experience with the mod.
- IC2 Teleporter - Huge energy costs and would require a plethora of other things to keep running, not realistic I'm afraid.
- IC2 Magnetizer - A simple notion and great for 10-20 block heights but I am not sure how well they'd work for multiple levels. Plus that metal boot requirement is a hindrance.
- Portal Gun - I'm using this for getting around quickly when outside but it's much like the Jetpack in that once it's out of your inventory you are stuck.
- Aerial Faith Plate - Not sure how well they would work for multiple levels and Long Fall Boots are a staple for protection but on the plus side they are fast, cheap to make and require no maintenance. I will play around with them and see if I can get something working.
- MystCraft Book Room - If I am understanding this correctly I could make an age (preferably something fast loading like the Void or flat-land), put linking books there which connect to every level and then have a book on every level which transports me back to the age with all of the linking books? If that's how it works then it sounds as close to perfect as it could be!
- Teleporter HUB - Similar to the above only with teleporters. I like the idea of a dedicated room which I can magically teleport to and from but unless I can find a cheap way to teleport (IC2 is too expensive) I don't think it's viable for me.
- Thaumcraft Levitator - Let's just say it won't work and we'll keep it at that, ha.
- RailCraft Elevator - Shouldn't be too expensive and it will look pretty good too. Not sure if I would have them running constantly or use a station-like setup but either way it's a solid option.
- Anything using RedPower - A possibility but something I will test when it is implemented.