I would never put so much chipotle en adobo as to be too hot for my eaters. Although seniors, they are adventurous and are used to chiles, being in Calif. Even a dab is good flavor. I ended up using The Hatch model (thanks whowantsdinner and a friend at another site), but I made my own sauce of green chile and tomatillo and extended it with canned sauce due to lack of time.
http://www.foodista.com/recipe/HB2RG8MN/hatch-green-chili-casserole-with-chicken

I also roasted a bunch of poblano and aniheim chiles to use in the layering. I poached the raw whole chicken breasts in the sauce for 30 minutes. It gave the sauce flavor and the chicken flavor. Also poaching whole, then dicing up the breasts helped to keep them from being overcooked in the end.

The overall flavor was good, sauce was VERY good, but it was still a pile of glop to me. At least I stuck to fresh (mostly) ingredients without too much fat or oil. I liked that nothing was fried in this, and the cheese was modest but not missing, only 2 cups per 9x13 pan (I used one of those Mexican shredded blends.)

if you have access to canned Hatch green chiles, there's a recipe on the can for a chicken, chile, cheese and tortilla casserole

Chipotle en adobo is wwwaaaayyyyy too spicy for seniors. If I were making this myself I would pour out a couple of cans of green enchilada sauce (incorporating tomatillo) into a large bowl. I would used corn as opposed to flour tortillas. Dip the tortillas in the sauce, getting 'em wet on both sides. Add your fillings and place seam side down in your casserole. REpeat and REpeat until finished. Tuck everything together.Top with queso fresco and bake at 400 to 425 degrees. To finish spoon a little crema over the top (Mexican sour cream). Serve.

I can get mainstream dried chiles like the guajillo, but not smoked peppers. I do have chipotle en adobo, though. A little spicy is okay. I have not seen tomato in enchilada sauce so I'm not sure. It will try it sometime for sure.

Another thing I am worried about is assembling ahead if it will get soggy. I'm googline around and I see some enchalada lasagnes. But I may have to assemble in the morning if I prep everything today.Still searching.

I make this a LOT - you can scale back the chilis if you want it less spicy, you caneven use roasted red bells if you don't want any heat at all - it make a great enchilada sauce:
http://www.food52.com/recipes/4086_ranchero_sauce

If you want to go in a different direction, consider making chicken creole. Here's my version of a Creole sauce that's really easy and scales well:
http://www.food52.com/recipes/6419_creole_sauce

Throwing together a green sauce for enchiladas is pretty easy. I usually just get a little olive oil, salt and pepper and lightly coat tomatillos, a little bit of onion, some jalapeno, and a few garlic cloves, placing all of it on a sheet pan and roasting it until you get a little brown on everything. It can then be pureed with some cilantro, some lime juice, lime zest if you want, and salt to taste. If it's too thick, a little water to thin it out is fine, but the tomatillos should have quite a bit of liquid in them.