2 Credits or 1 Credit...

For 14 nights we did 10 table service and 2 signatures we found we had left over counter service credits as with the snacks its a lot of food, however we had days we weren't on site and were at universal so we made up the credits to use at signatures it all depends on your family, if you wanna do a lot of signature it might be worth paying the extra to upgrade to the delux plan which is 3 credits a day to use how you wish.

If I had the standard dining plan I would do one credit restaurants as one counter service and one table service a day felt like a good amount of food for us. If I had the deluxe I would opt for more two credit restaurants.

I usually just do 1 or 2 signature restaurants per trip. The budgetary constraints for me are just too great to double up on credits every time. However, I suppose that if you did double up on the credits and then ate counter service when paying out of pocket you might recoup the loss.

This is kind of a fun question, since we aren't dining plan types. But if Disney is willing to give you that perk for "free"...
I think I would use it at mostly one credit places. Maybe just one signature.

Same as mousdreamig above, I'd stick mostly to 1 credit table services. We just don't appreciate the signature experience and food enough to want to do more than 1 or 2.

Can ii swap out the free dining for a room upgrade

Purchasing the Dining Plan has its advantages in that you know what your food costs will be before you leave home. However if you have a DVC membership or are an Annual Passholder, the $100 fee to purchase a Tables in Wonderland membership can be recouped very quickly. The 20% discount also covers alcohol as well as 100% of valet parking. There are some black out dates, but most of us on this forum choose to go to WDW during the least busy times of the year whereas most of the black out dates are in effect at the most busy times of the year. Keep in mind that an 18% gratuity is automatically added to your bill. But since most people tip 15 - 20% your 20% discount is still saving quite a bit of $$. Just wanted to toss out another option!

Truthfully, yes. I always take a room discount over free dining.

In that situation, I'd probably limit the amount of signature dining places I'd use because the quicker I use up the credits, the more meals out of pocket I'll have to pay for. So like everyone else, probably 1-2 to signature dining places and the rest being one credit.

I would pick your favorites regardless of credits and make up any 'gaps' using the snack credits.

The dining plan is great but there was so much food included that I ended up eating CS meals for the sake of it. I could have easily booked a couple of 2 credit meals.