Depends on what sounds good with the song, of course, but have you ever tried triplets? For example:—

Thumb alternates between bass strings, each finger plays the same string each time (although you can experiment with that).

T, 1, 2, T, 1, 2, T, 1, 2 / T, 1, 2, T, 1, 2, T, 1, 2 / etc. Another one is

T, 1, 2, 3, 2, 1, T, 1, 2 / T, 1, 2, 3, 2, 1, T, 1, 2 / etc.

Nice flowing effect. Good for some songs, maybe a bit to "sweet" for others.

Don Firth

first line corrected by mudelf ;-)