ETA Oct, 2011 - BLAB no longer has FP. Those machines are now dedicated to Star Tours. And BTMRR FP is no longer connected to the DL network as of August.
It depends on what you want to ride, how many times you want to ride it, and when you show up at he parks. Note that if you show up two hours after the park opens you will have lost about three FP opportunities.
So lets imagine two possibilities. First, the smart DLR visitor who arrives at the gates at least 20 minutes early (30 minutes is better). Second, the not so smart visitor who arrives two hours after the park opens. Aside from the fact that the smart visitor was able to get on 5-12 rides in the first two hours minutes and can then focus on other rides that always have short lines, lets look at the FP implications.
Facts to be aware of:
1. DLR accepts FP any time after its one hour window opens until park closing
2. After you get a FP, the next time you can get a FP is set by a minimum of 45 minutes or a maximum of 120 minutes, depending on what the return time is of the previous FP.
3. The DL and DCA FP systems are not connected, and thus FPs at one park have no influence on the other
4. The examples below are illustrative only - the real world of your group will dictate how practical it is to pick up your FPs. No one wants a FP Nazi dictator in their group, but everyone likes to avoid lines. You need to find the right balance for your group. In addition, it depends on where you are physically in the parks. If it is not practical to get a certain FP, then get the next most practical one when you have opportunity.
Smart Visitor:
Assume DL opens at 8AM - this is the order you should get your FastPasses in an ideal world. Modify this as necessary to fit your group, location in the parks, and available time.
1. Space Mtn (get FP @8:10AM - next FP time will be 8:55AM - you can use this FP anytime after 8:55AM)
2. Splash Mtn (get FP @8:55AM - next FP time will be 9:40AM - you can use this FP anytime after 9:40AM)
3. Indiana Jones (get FP @9:40AM - next FP time will be about 10:30AM - you can use this FP anytime after 10:30AM)
4. Buzz Lightyear (get FP @10:30AM - next FP time will be about 11:15AM - you can use this FP anytime after 11:15AM)
5. Big Thunder Mtn RR (get FP @11:15AM - next FP time will be about 12:00PM - you can use this FP anytime after 12:00PM)
6. Autopia (get FP @12:00PM - next FP time will be about 12:45PM - you can use this FP anytime after about 12:45PM)
It really is not that hard to do the above by 2PM as long as you start at 8AM. If you really want to focus as above, you can get one of everything by lunch.
There is one other FP opportunity at DL: Roger Rabbit. Roger Rabbit is not connected to the DL FP system and you can get one anytime you want without conflict with other DL FastPasses.
Further, I no longer get FPs for Autopia after realizing the FP return line can be a 25 minute wait. If I only had one day at DL, I would get an Autopia FP. But if I had multiple days, I would plan Autopia for an early morning thru the standby line.
Not So Smart Visitor:
Assume DL opens at 8AM, this visitor arrives at 10AM.
1. Space Mtn (get FP @10:10AM - next FP time will be about 12:10PM - you can use this FP anytime after about 3:00PM)
2. Splash Mtn (get FP @12:10PM - next FP time will be 2:10PM - you can use this FP anytime after maybe 6:00PM)
3. Indiana Jones (get FP @2:10PM - next FP time will be about 4:10PM - you can use this FP anytime after maybe 9:00PM)
4. Buzz Lightyear (get FP @4:10PM - next FP time will be about 6:10PM - you can use this FP anytime maybe 6:10PM)
5. Big Thunder Mtn RR (get FP @6:10PM - next FP time will be about 6:55PM - you can use this FP anytime maybe 6:55PM)
6. Autopia (get FP @6:55PM - next FP time will be about 7:40PM)
And, again, you can get Roger Rabbit any time you want.
OK, so what's the difference?
Well, in both cases the person got FastPasses for everything. But in the second case, one had to stay all afternoon at the parks to do it. In the first case, one could take a break back to a hotel or something and still have all their FastPasses. Or they could get FastPasses for a second ride on something. Or they could go to DCA and start collecting FastPasses. Or they could use their FastPasses in the afternoon when all other rides have the longest lines.
The not so smart person cannot ride many of the FP rides until the evening.
At DCA
Similar logic holds. Here is the ideal order to get FastPasses:
1. Soarin' over Ca
2. California Screamin
3. Grizzly River Run (on a hot day - otherwise this can wait til later)
4. Tower of Terror
5. Mulholland Madness
All of the DLR FastPass tips and tricks are discussed here:
http://www.disboards.com/showthread.php?t=885132
http://mousepad.mouseplanet.com/showthread.php?t=43193