Day Trip to Dresden -- on own or with a tour?

Todd,

If you do some research with a good guidebook and the internet, you should be able to plan an efficient day trip to Dresden. The nice thing about doing it yourself is that you can include sights that specifically interest you. You can also leave as early as you want and come back later, as you won't be tied to the schedule of the tour.

The magnificent Frauenkirche is worth a look and also the Bundeswehr Military History Museum (if that sort of thing interests you).

For this, I think I would take a train there and go on one of the walking tours offered by the TI. Perhaps book it ahead of time. I think they are only 12-14€. This way you aren't stuck on a bus for 2 hours each way. The train is faster and you have more time in Dresden.

The museum to visit in Dresden though would be the Green Vault and this is not porcelain or paintings. This is a gold, silver, pearl, jewel, ivory extravaganza like nothing you have ever seen before. Hard to explain, but it will wow you with the creativity and the excess of fancy.

There are two Green Vaults in Dresden. The regular Green Vault has all sorts of beautiful objects; it's worthwhile, but the Historical Green Vault is a cut above and pretty nearly unbelievable. The Historical Green Vault requires a timed entry ticket. No one has reported here that they were unable to get such a ticket on the day of arrival, but I cannot guarantee what will happen when you walk up to the ticket window. It should be easier for a solo traveler to squeeze in.

I note that you are (apparently) male. It's entirely possible that the Green Vaults appeal more to females, on average. One of the other museums in the complex has a lot of impressive armor. Not to be sexist, but perhaps that would be more your thing. (Armor bores me after about 3 minutes.) I really enjoyed the city walking tour arranged by the T.O. I don't remember what time it departed, but it provided some historical background that I found helpful.

Well, if he's male, maybe he would enjoy the two galleries of nothing but the Cranachs, with plenty of flesh exposed. Just kidding. The only value added I can see for a guide is making clear what's Wiederaufbauen (rebuilt) and what's original. There are so many interiors to see in Dresden that I'd rather not be dragged around in a group. However, as hinted in another's post, I kind of prefer to do my own research. For example, you can't "walk" to the Military Museum and its landmark addition by Danile Liebeskind. This remarkable museum is just the kind of collection that might appeal to someone who is easily tired of porcelain and canvas hung on the wall!

I had a look at one of the offered tours. Bus to Dresden, guided tour 'til noon, afterwards you can explore the city on your own. I guess taking a train is a bit faster, but a short guided tour ispretty good to get an idea about the destruction and rebuilding of the city (what you see today is just a very small part of the former old town).
To me these tours look like a pretty good deal, but if you are really into museums the guided tour is a waste of time since Dresden has so many world-class museums. Both Green Vaults, the Old Masters, the porcelain collection.... btw: the Rüstkammer with the Turkish Chamber was expanded some days ago. There is a new section with the electoral wardrobe of the 16th and 17th century.
PS: keep in mind that the Zwinger with the Old Masters and the porcelain collection is closed on Monday, and the castle with the Green Vault(s) and the armoury is closed on Tuesday.

"For example, you can't "walk" to the Military Museum and its landmark addition by Daniel Liebeskind."

While it's a bit long for a walk, there are Trams right outside the main rail station and very easy to get to the Museum with those. I can't remember the route that I used, but could probably find the information in my trip notes.