I think it varies from person to person and also depends on the terrain that you are spending most of your time on.

I have terrible knees, so I will rely a lot on my granny gear to get me up hills, especially steep ones that occur late in my route, early in the season when I'm getting back in shape. I'd rather slowly spin my way up a hill than dismount and walk it. If I can do the same hill later in the season using a "harder" gear setting and still not feel like I'm mashing, then I view it as progress. By end of season I hardly use the tiny gear at all. And then I start over again the next season.

Then again, I just moved to a place that doesn't have a lot in the way of hills, so unless I travel out of the region with my bike, that little gear is probably obsolete.

With a triple you have to be careful not to cross-chain your gears. Otherwise, I'm glad I have it.

Did the bike shop tell you how long you would have to wait for the double? If that's what you want and you feel strongly about it, I'd ask about an estimated delivery date and then make a decision.