I found out a really cool hack to fly faster and it works in 1.5.1
open level.dat with nbt explorer ,then data, then Player, then abilities, and there you will find an ability called flySpeed. This does what you think. It is set as a default of a meesly 0.05. Ramp it up to 0.5 and save. Next time you log on, you will fly pretty fast.
This is confusing, So will make a video soon about it.
If you use Singleplayer Commands, which is a very simple mod that doesn't add anything except some helpful commands, you can use the command /setspeed and then you can set your speed. 1 is your normal fly speed. Anything higher than 1 will make it xx times faster than 1. The one thing is that sometimes chunks don't load instantly if you're going on a really fast speed (over 5 usually). Or you can just create a railway system between the bases, which is pretty fast. Speed 2 potions are also a fast means of measure. And the last thing I can think of is go into creative, do /give [your username] 137 (which is a command block) and set it up so you just have to click a button to activate the command block that teleports you (ex. /tp @p 155 64 -243) and have the same one in your friends bases.Keep in mind you have to be in creative mode to setup command blocks, but it would be a quicker way. The last possible thing I could possibly think of is using the worldedit features of SPC and copy and paste you base closer to your friends base, but could possibly not work if you're on a mountain or such. That would be the last last last last LAST thing I can think of.
The fastest speed you can get while flying in vanilla would be to first drink a speed 2 potion, then you fly foward, and while pressing foward, type 1 time CTRL. It will last when the running and/or the speed 2 potion will last.