Remathilis
Legend
There is a flip-side to this, though: whereas the rules for suprise when the party has a ranger are fairly clear (3 in 6 rather than 2 in 6) the rules for suprise when the party has sneaky thieves in it are not clear at all.
And here is where 2nd edition fixed things.

Rangers and Thieves used the same Hide in Shadows/Move Silently mechanic, which if successful assumed the character was silent/hidden. This could easily equate to the "Silenced/Camouflaged" modifier on the Surprise Modifiers table (-2 each). You could assume that each successful check granted a -2 to your surprise roll, for up to a -4 on a 1d10. If you were an elf or halfling in leather armor, it could go up to -8 (max if you made both checks), which is pretty ninja!
Of course, that requires some reading into the rules a bit, its not as spelled out as it is in 3e on. However, the HS/MS rules work well if the DM decides not to call for surprise rolls and instead eyeballs it via successful checks alone, which is equally viable.