Have an issue where the clutch, when it sits for a few days, requires me to "pump" it up a few times before it will operate. Once I do that, it's okay. Thoughts? Should I bleed the lines? Is it possible it's something more serious?
There are a few questions that come to mind. Has the system been worked on recently? Yes = may need bleeding. No = Master may have worn seals that allows some leakage and pumping just rebuilds the pressure required to move the throw out/clutch. Does the system have old fluid? Yes = flush with new and it may revive the seals You may drive up to a red light or stop sign and discover that you need to pump again to find a gear. Its your master telling you its time. If you replace the master you should go ahead and do the slave and the flexible hose connecting to the slave as well. Bench bleed if its a DIY.
Before you throw a bunch of money towards parts you may not need to replace, why not just spend a few hours of labor and examine all the hoses and fittings, check for leaks, tighten the fittings, and bleed the system?
Does the rubber hose at the slave cylinder have any cracks? Does one of the fittings look a little wet? I know it may be hard to tell if there is a lot of oil on everything down there under the car, but take a rag and wipe off all the fittings and then check them again in a week (or after a couple of trips). And don't forget to check the carpet for fluid leaks (up under the console where the clutch rod goes through the firewall).
If, as you say, the clutch works fine after you "pump it up", it sure sounds like air is getting into the line from somewhere. But if a few clutch pedal pumps squares it away, that air is probably getting pushed out the at the same place it got in (along with a bit of fluid).
FWIW, I have heard the Mityvac MV-8000 makes the bleed job much easier.