Ahh, okay, I was looking at the subject of this thread and assumed you were talking about a TDS744A.
Yes, the 544A has a ton of caps on both the Aquisition board as well as the CPU board. I've used Panasonic AHC and VHC series caps from Digikey, and I've also used Nichicon UCD series caps from Mouser with no problems. Like I say, I usually use the price of the caps as a guage for which caps to buy. I don't think the original caps that were used on these scopes were either high temp, long life, or any other special characteristics. So in my opinion, just about any cap is probably better than the original ones.
The other thing to keep in mind is that at the time these scopes were first designed and manufactured, SMT electrolytics were just starting to enter the scene. My guess is these caps had problems with their reliability, and nobody knew about it until years later when they discovered that these things leak their electrolyte. And by that time it was too late to make any changes as the units were out of warranty and/or out of support, and Tek was already well into designing the next series of scopes that didn't use the electrolytics.
The only thing I would consider replacing the electroltyics with would be a ceramic cap. I've looked into that, but you'll spend a small fortune buying ceramic caps of the same value as the electrolytics that are on there....and I'm not convinced that the cost would be worth it. In my opinion, using decent quality electrolytics as a replacement will likely last a very long time. Some people may disagree with me here, but that's my opinion for what it's worth.
One other thing. The front panel board also has electrolytics that should be replaced, I think around 6 of them. But 2 of the caps are actually the wrong voltage for the circuit!! There are 2 of a 33uF/10V cap used on the +15V and -15V rails. This is a design problem, and you should replace those caps with a higher voltage rated unit. I used a 33uF/25V cap in the same case size for those caps.