[Seth]

If making distance more meaningful, or more of a factor in the choices players, choosing to use Gates only instead of FTL drives is really just trading one popular implementation of sci-fi tech for another. I would say consider what is it you're trying to accomplish and more specifically, how you wish to accomplish it. Being in control of all the game mechanics you can scale it to be as powerful or as gimped as you like and anywhere in between. There are a lot of easily conceivable factors which could prevent them from letting players zip around to any part of your galaxy at will.

Take EVE for instance. The cost of fuel (and distance limitations per jump) make it impractical to constantly jump around unless you are fairly rich. However, scaling the price of fuel, or the availability to mine/obtain is essentially a throttle on how often someone will jump.

As another example, BSG has the interesting limitation of needing to spend time calculating a jump before they can actually make it accurately. If used the same way in a game, you can effectively limit a player's ability to jump to whatever abitrary base time period you choose; then reducing that amount of time based on skills and/or ship equipment (such as better computers).

Gates do add the bonus of forcing travel flow through specific points though, which allows you to design things around that concept, such as gate sentries, turrets, or whatever. However you can also place restrictions on jumping by requiring players to acquire something like "starmap data" for a point before they can warp to it. It could be an item that is acquired from NPCs or you can physically require them to go to the point (or someone with the skills and equipment) and collect the information and turn it into tradeable "starmap data" which allows a jump to that point. If you don't want that sort of thing to be a commodity just put it right into the computer so they can use it, or use some variation of no drop. Of course you can also do a mix of both.

Obviously there's probably a lot of holes in some (or a lot) of my conjecture and you may have completely different reasons for wanting only gates, or you may just hate the idea of warping as a mechanic. However, I was simply hoping to provide an alternate point of view on the issue.

Edit: I just realized that I was going on the assumption that you were describing something like EVE where you can (mostly) move within a system or general area unassisted but require a gate as a mechanism to transport you between systems/areas. If I assumed incorrectly then some of what I wrote is probably out of context though I think a lot of it would still be valid.