Using miles. What would you do?

OK, here is the scenario. It's a bit complicated, but I'm sure some of you have been there! I've got just over 50000 miles at the moment, soon to be 58000 odd after my latest spend and bonus 5000 miles with the new Virgin card. I've got a UC flight in November which I'm paying for which will take me upto about 80000 miles.
I'm going to Miami next March 22nd returning 7th April. I'm just trying to think of the best way to use my miles for this trip:
* Book a reward economy ticket now and then it's all done. I'm worried if I leave it, the reward flights won't be available, especially as my return flight is on Easter Saturday
* Wait until I have a few more miles and book a PE flight, which probably wouldn't be until late November. Will I be lucky to get a flight out and back at that late stage?
* Buy some miles now to try to get a PE reward flight
* Forget the reward flights and try for an upgrade to a purchased ticket
I know there are a few other scenarios. Life is complicated and I'll admit to not being that savvy. Let me know what you would do, or if there is something glaring I have missed.
Thanks for any advice.
Phil
[y]
I'm going to Miami next March 22nd returning 7th April. I'm just trying to think of the best way to use my miles for this trip:
* Book a reward economy ticket now and then it's all done. I'm worried if I leave it, the reward flights won't be available, especially as my return flight is on Easter Saturday
* Wait until I have a few more miles and book a PE flight, which probably wouldn't be until late November. Will I be lucky to get a flight out and back at that late stage?
* Buy some miles now to try to get a PE reward flight
* Forget the reward flights and try for an upgrade to a purchased ticket
I know there are a few other scenarios. Life is complicated and I'll admit to not being that savvy. Let me know what you would do, or if there is something glaring I have missed.
Thanks for any advice.
Phil
[y]