Yeah, you can do this. It was more intuitive in older versions of the player, but it's still possible.

So let's say you want to make a playlist of all episodes of Stargate SG-1 and Stargate Atlantis, sorted by air date. This is a good example, because there are crossover episodes, so watching the series in order has advantages.

You need to start by creating a smart filter that contains the episodes you want to add.

1. Go to your TV Shows Library.
2. Select the Library tab.
3. In the upper-left corner, change the first filter (which is probably set to "All") to "Advanced Filters."
4. In the upper-left corner, change the second filter (which is probably set to "TV Shows") to "Episodes." This is a critical step you need to do first to ensure that the individual episodes of a TV Show are sorted by air date. Otherwise the TV Shows will be ordered based on the air date of their first episode, which isn't what you want.
5. Use the first filter rule to the following: Show Title contains Stargate
6. In the upper-left corner, change the third filter (which is probably set to "By Show") to "Release date."

You will now see that the list of episodes below has been sorted by air date.

Note: The first time you click on Release Date, I believe it sorts it in descending order, as indicated by an orange arrow to the right pointing down. Just select it a second time to make it ascending order.

7. Click Save As and add it to the playlist, smart playlist, collection, or smart collection -- as you see fit.

Voila, you can now watch 314 episodes and movies of Stargate in the intended order!

Hope that helps.

Plex meta manager can import custom playlists, and can do about 15 other things

I would look into QuasiTv for this, I haven't done it myself but it has some really cool stuff you can do like making a dedicated cartoon Network channel or just making channels based off of broadcasting stations of what content you have.