Thanks so much to all of you for your comments!
Janet, JAileen, kkards, Angie, Suz, Gigi, Brooklyn, unfrumped, Style Fan- The teal ended up winning the day. Taking pictures outside was key. It was so clear that the chartreuse was overpowering me, once I could see it in natural light. When I started looking for a trench, I was hoping for teal, but open to anything that wasn't black or khaki. Finding chartreuse and watermelon was an added bonus, so that I felt like I had choices and wasn't settling.
Christina F., Katerina- the shoes I'd wear with the coat are all either black or taupe/nude-for-me, and the bags are all black. Adding a couple bags is another one of my style goals for this year.
Runcarla- I loved the idea of finding a scarf that incorporates the colors! So, I ran over to Nordstrom's, tried on the four scarves in the finds, and settled on the third one (Pink Magical Botanicals print.) I love it with the coat, and it works really well with my navy and teal dresses. Best of all, I leave for a conference tomorrow, and am thrilled to have something new to wear!
unfrumped- There's a back story to the chartreuse. A few years ago, an SA at Nordstrom's pulled out a chartreuse jacket for me to try. It was on sale, last one in the store, and just happened to fit perfectly. And, I didn't buy it, because I was being very disciplined in my shopping. I've regretted that decision so many times. Anyway, one of these days, I'll find the chartreuse/citron jacket of my dreams.
smittie- my heart is with you on the chartreuse. But, I had to agree with everyone who thought it was wearing me. I'll be adding chartreuse in smaller doses, though.