I have about 350,000 miles with United right now. I am keeping them active for the time I can get back out there!!!
Yes, things have gotten much harder in recent years... some tips:
1. Think of other ways you might use miles - spoil yourself with an upgrade!
2. forget trying to get limited awards to popular places in peak times - the airlines will want to sell seats rather than give them away. So Disney in the summer? forget it! Florida in the winter? nope.
3. If you DO want to try to go to a popular destination - BOOK EARLY!! Inventory often opens up around 335 or so days in advance. So if you can plan a year or so out... do so.
4. Be flexible with dates... this will often help find an award
5. Think outside the box a little in terms of destinations. Also consider partner airlines - For example, let's say you want to get from LA to London. Air New Zealand also flies the route, so does US Airways (via PHL I think), and so does Lufthansa (via Frankfurt).
6. I never use my miles for domestic (US or Australia) flights in economy(coach). Tickets are relatively cheap enough there's no benefit there. Instead, save them up and splurge. In 2004 I spent 150,000 miles for a First Class award ticket from Melbourne (oz) to London on Singapore Airlines. A ticket valued at roughly $12,000 at the time. That was one of the mose decadent and amazing experiences I've had
and it was sensational!! I'd never ever pay for that with cash... but with miles... you betchya!
7. If you have elite status with an airline (so on UA, that would be Premier, Premier Exec, 1K etc) often it is easier to obtain award seats.
In some ways it's nowhere near as worth it as it used to be to play the game, but if you play your cards right you can still find options to use the miles.
Consider less high profile routes and destinations, and also consider where your airline of choice (or its partners) fly to the most - with bigger planes - which will give you more opportunities. So for example United isn't fantastic with New York service (compared to, say, Continental)... but Chicago and San Francisco? Denver? Yep, go with UA.
Good luck!!!