I'll throw a couple things your way. You mentioned using a darker honey. Definitely give this a try. I prefer using darker honeys. They seem to ferment out better for me, as well as provide a fuller flavor at the end. A dark wildflower honey is pretty much my favorite to use. I'm also a big fan of Japanese Knotweed honey if you can find it. It's a very dark amber color and has some great caramel flavors.
Another thing you can try is a bochet mead. This will involve boiling a portion of your honey to darken and caramelize it. I have a 1/2 barrel batch going that I just back sweetened with a gallon of caramelize honey. Forewarning, if you boil honey make sure you use a pot that's around 4 times the size of your honey. It's also going to make your entire house smell like toasted marshmallows and caramel.
You also mentioned using malts to add color and flavor. I've done this a couple times. In general I haven't been thrilled with the results. The last one I did with malt was a smoked braggot. I made a batch of wort using a base grain, crystal, and smoked malts (no hops). Then I added a bunch of honey and fermented. It initially came out pretty good. But what I ran into was the flavor change was very unpredictable as it aged. For a few months the mead was great. Half a year later it seemed that the best flavors were falling off. If you want to try using malt, I'd say go for it. But malt may have an impact on the maturing schedule you normally use for your mead.
And your last point, about using a higher gravity. This also is something I do regularly. Not all, but most of the meads I make have an OG of 1.120 - 1.125. With this you may find that your batch doesn't ferment out completely dry. This works well for me because I prefer sweet and semi-sweet mead.
Another thing you can look at is adding some fruit. You'll see different options on when and how to add fruit, so do some looking around to see what might work best for you. For myself, I prefer using fresh fruit over extracts. I usually get a batch of mead to the point it's a few months out from bottling time. Cut the fruit up into a carboy (or whatever container you're using). Rack the mead on top with an addition of potassium metabisulfite. My usual amount is about a pound of fruit per gallon of mead. You may want a little more or a little less, but this has always given me a good baseline. Give it 2 - 3 weeks and rack it off.
Cheers and good luck!