I would also recommend one that will read DC Amps, up to 10 A.  That is
useful for testing for things draining power, and how much power items are
using.  I bought a super cheap digital one from harbor freight tools a
couple years ago.  It has up to 10A, and all the other usual ranges.  It
also has a built in battery tester for 9v and 1.5v batts that puts some
load on them while testing.  And a transistor tester, which I will never
use.  I was going to hack it open and use it as the basis of a
comprehensive electrical system monitoring display for the van.  I was
going to use a selector switch so that I could check voltage on both
batteries, and current going into or out of the aux batt, and maybe output
voltage from the inverter.  Haven't gotten to that yet, but the stupid
little meter is still working.  I have really zapped the Ammeter section of
it a couple times when I forgot it was in that setting and went to measure
battery voltage.  It still keeps working.
Edward