Another pattern is the "Don Maclean" style, which I like. He often picks with the thumb on 2 consecutive notes, so for example playing G you'd pick bottom G with the thumb, let it fall through and pick D on the next note, then play the rest of the fingers. Since this gives you two consecutive "purely-thumb" bits, it leaves your fingers free for longer to put melody in, and the 2 low notes give a nice "ripple" effect to the arpeggio. Alternatively, if you play 4 measures with 2 thumb, 1st finger and 2nd finger, this leaves the 3rd finger free to ornament the arpeggio with some melody.

Grab.