What tuning(s) do you use?
This used to be an easy question to answer. I grew up playing in D6 tuning (a, d, f#, b) with a low A string like all students of the Doane ukulele method. It wasn't until my late-teens that I started to fool around with other tunings. Nowadays I travel with four ukes: one with a high 4th string and another with a low 4th string, the Beltona slide which I tune either a, d, g, b or g, c, f, a depending on the song, and the beansprout banjo which I always have in high 4th tuning.
There are advantages and disadvantages to both low 4th string tuning (a.k.a. "linear" tuning) and high 4th string tuning (a.k.a. "re-entrant" tuning); otherwise I'd just travel with one ukulele and forget about it. Re-entrant tuning is great for vocal accompaniment, jazz chording, and campanella-style playing (à la John King). Linear tuning is better for ensemble melody picking, classroom instruction, lead picking and solo arrangements that involve moving bass lines. Different tools, same tool kit.