"We will arrive in Nurnberg around 11:30 am have the afternoon and most of the next day to sight see."
With that first plan: after landing, you'll probably have a couple hours tied up with bag collection, transit to hotel, check-in and unpacking. You'll probably want lunch too. So perhaps some of the afternoon will be available. If you have most of the next day as well, that sounds good, as long as your sightseeing goals in Nuremberg are limited. Some things like the Nazi Doc center and rally grounds, take time.
But your plan on Day 2 was to arrive in the early evening in Rothenburg - and on Day 3 you're leaving for Füssen. Many do this journey along the Romantic Road (which is nearly 500 km along mostly pokey country roads starting from Würzburg - not sure from Rothenburg but only slightly less I'd guess.) If that's your plan, I think you'll find yourselves arriving very late in Füssen if you stop and investigate some towns along the way (which is the whole point, really; the road itself isn't very interesting.) And back in Rothenburg, you'll basically have time for dinner, overnight, and breakfast. That's not much.
So yes - a 2nd night in Nuremberg would allow a little more time in N'berg, and most of Day 3 for Rothenburg. Then you could drive south to Füssen on Day 4 (from dawn to dusk if taking the Romantic Road... some spend 3-4 days on this route.) But since you have the extra time, I suggest you add a night on the RR mid-way between R'burg and Füssen. Nördlingen or Harburg might be good.
So that spends two of the 5 nights you asked about...
I would use the remaining 3 nights as follows...
1 night to break up the long drive from Füssen to Burg Liebenstein... Tübingen is a good choice. Or perhaps drive a bit further to Bad Wimpfen, also on the Neckar River (which provides a scenic drive as well.)
2 additional nights in Franconia (Nuremberg-Rothenburg area) to see some of the places previously suggested (Bamberg, Iphofen, etc.) Right now you have 1 night planned in Nuremberg (2 if you take my tip above) and 1 in Rothenburg. But I would definitely reconsider this whole stay. Why not make Franconia your area for the "unplanned"?? It's perfect for that. What I mean by this is picking one central town for your 4-5-night base, so you need not worry about having a place to put your heads - but keep your days completely open and freewheeling, do your planning as you go, and make day trips as the mood suits you. There's no reason you have to stay in Nuremberg just because you land there, or Rothenburg either. Find a place to stay in between for 5 nights. Or if you prefer, spend Night 1 in N'berg and Nights 2-5 in the unnamed base town. Neustadt-an-der-Aisch is a simple, attractive town I have used with my family as a Franconian base. I's positioned so that trips to/from Nuremberg, Bamberg, Würzburg and Rothenburg are nearly equidistant. Bad Windsheim and Iphofen are very close. But there are many small towns that might work for you. Iphofen itself has a good location for these outings.
Happy planning. Hope this helps.
