It would be nice if the conversations were a bit more diverse, on the planets, and when hailing. So you can threaten someone to drop his cargo when hailing, and on bases you can actually influence the conversation yourself (so the NPC might give you a well-known, or a really special rumour).
Also, more variety in the random missions. How about going back to Hovis' base and be able to race against random people there, and build up a career as a sportsman? Or an escort mission? Or even, a search mission. You get the coordinates of 4 sectors and somewhere there the enemy is holding some guy hostage. You kill all the enemies, and tractor in your guys escape pod. Or, if you're a freighter, a difficult trade run through dangerous enemy territory, which will give you a bonus.
I agree that it would be fun to own a base, but there should be some requirements to it. Your level has to be 30+, you have to have 4 wingmen to help you build, and you have to have enough money. When you start building, a timer starts in which the nearest enemy faction will atttack you. Your wingmen are building so you have to handle them on your own. When the base is done, you have to equip it with turrets ofcourse.
Someone said earlier that when you're level 5 or higher liberty space is virtually useless. And none of the house ships can compete with the Eagle or Sabre. So why not give every house a Very Heavy Fighter of it's own?
Also, I felt a bit left behind after the Single Player missions. Sfwarlock on this forum had a really great idea, of having Juni, King and Tobias stay at Manhattan, Pittsburgh (or another planet) and Leeds. So you can still meet them, and they will make a comment on your current rep and status. What they should have done was have Juni hang out in the Manhattan bar. Whenever you show up, she should give you a hug and some info, like "Hey Trent, good to see you again." and then something like "I hear you're tight with the Corsairs now. I hope you're just scamming them long enough to get some good gear." or "You better watch yourself. I just heard a couple Bounty Hunters talking about the price on your head."
I think an admin of this site should mail the best of these requests to DA!