I went back to play Mace Griffon bounty hunter on my xbox and I love how you can leave your cockpit and walk around your ship, although quite small, then go back and pilot the thing. Are there any modern games that feature that, but can also be upgradable, such as making the ship bigger and adding more rooms that you can walk around in? I think Star Wars galaxies had an expansion where you get a ship which can be decorated inside, and you could throw parties with your friends, that sounded awesome.
There are several voxel-based space games in alpha where you build the ship from scratch and upgrade from mining asteroids and stuff. Blockade Runner is the one o remember off the top of my head, but it's the most incomplete one.