So, you've worked your way up ship classes, whether by trading, piracy or serving loyally. You jumped into a Neptun, maybe even nabbed a fancy shmancy Avalanche, and then went after the reeeeal big guns, and you've got into a Stonewall or Gettysburg, at the cost of many Bothans. You've got those big shiny guns you always wanted, and you can make the Kessel run faster than the Falcon.
So now what?
Whether a fleet admiral or a pirate lord, you spend your time slogging through lengthy siege after lengthy siege. It's not that you can't win them, because you're becoming the scourge of the universe and it's a miracle the enemy fleets stay around long enough for you to shoot them!
Fleet admirals can speed things up by going after starbases and smashing through them early on, but if you're a poor pirate lord you're crap outta luck. Sure, as a pirate lord you have to balance your planets, but lets face it, you have no idea what to do with them as long as the loyalty is going up.

So what?

I think that this is a point in game where many people give up and enjoy early retirement. It loses the fun factor of the early game, and the danger as well. Apart from the occasional battlegroup that dodges every shot for several rounds in a row, nothing even comes close to scratching your shields. Personally, I don't have a problem with this, I worked hard to get this powerful! But the problem is that the siege still drags on for nearly a year, no matter how many battlegroups I blaze my way through, and I don't have anything else to do. Doubly so when you're a pirate lord starting from a single system.

Speaking of single system, where on earth am I magically getting all my battlegroups from? I talk to my fleet commander, and she proudly tells me I have one battleship and two cruisers, and then my radar has me surrounded by friendly battlegroups. Now I'm no Dane but something is rotten.

So what am I actually saying? Give us more to do in lategame. Give us planetary management that means something, maybe make it more tied to our personal accounts and the financial power of our wars. Give us a more meaningful fleet management system so that I can order my battleships and cruisers and even set objectives like "Steal all those damn avalanches you can find".
Speaking of fleet management, when running fleet missions, surely I should be able to requisition my reinforcements, not wonder whether High Command (wait, I should be High Command surely?!) is going to give me a trio of Neptuns that can handle the mission on their own, or a pair of Thugs and a Hellcat!

Most of this is written from the point of a Pirate Lord, but Fleet Admiral also runs into this problem, although if you can get good at regular starbase demolition at least you can force early closes to sieges. Also yes I have a crush on the Avalanche. But not quite enough to keep me from my Stonewall. Pew pew eat 80cm Disruptor cannons at 8 shots a round!