Tips
As a gm I get annoyed when players aren't paying attention when it's not their turn. We have a pretty varied group of players when it comes to gaming experience, it ranges from a couple months to 15+ years. So naturally some turns take a little longer than others and people tend to get distracted.
So I'm trying to come up with ways to keep the players more engaged when it isn't their turn. I've seen some optional rules that have the players making defense rolls instead of just relying on their AC to protect them. And while I like the idea of that, I don't want to make things to complicated for the newer players, or bog things down with excessive dice rolling. I've also read where you can have the players roll the monsters attacks and damage against themselves. Down side to that is it gives them access to more info and can encourage meta gaming. Although it does have the added bonus of making the players curse their own dice for rolling good.
Does anyone else have any other ideas or recommendations?
Hmm I tried those options you mention. Sure it makes defending players a bit more engaged as their own roll dooms or saves them, but in the end it just means the DM rolls alot less and the players rolls instead, usually taking up more time.
Also players are likely to pay attention when THEIR character is attacked anyway so it hardly helps much. Could be a nice way to "take it up a notch" in a stagnant game, but it won't directly adress your problem.
Here are some tips that might help:
1. Try to limit decision time. This is probably the #1 time thief far more than just rolling dice (which takes a few seconds per toss). If need be use a time or something for problematic players, or start counting after a while. If time runs out the character automatically takes a Delay Action. While it may sound harsh, it lets the acting player think about it (and hurry up) while someone else gets to act. Delay is your friend.
2. Make sure calculations and dice rolling is speedy. The new players might need some help. At least help them pre-calculate their normal attacks and relevant modifiers so that they only have to add/subtract situational modifiers. It may also help to roll attack and damage rolls together, if attacks are seperated.
3. Avoid looking up too many rules. It's usually better to make a Ad-Hoc ruling that spending 10 minutes going though the book to find an obscure rule. Especially for cases where the outcome does not matter that much. If it's a life or death scenario for a PC then you should take the time needed, no fun losing a character because of DM error.
4. Spells, special abilities etc. tend to slow down the game. If your new players play spellcasters try to help them prepare spells and how they work. Copying or making cheat sheets for certain spell could be helpful. For the veterans make sure they know how their spells work and or/look them up before they cast it, preferably before their turns come up.
5. This is a group game, not single player. If one player get's too much attention and "camera" time the others might get bored and not pay attention. If the other players start reading stuff, checking iphones or playing other games that's a sign something should be done. Sometimes making the player pay attention or lose info important to his character can help, and sometimes limiting other player's game time is what it takes.
At the last descriptions and asnwering player questions also takes time. This is also an important part of the game that can't be skipped. However try to be as clear and concise as possible, give the players the info they need and answer their questions with relevant details. If they ask too much or demand too much detail, require them to spend actions (usually a move action) and take perception test. No, the fighter won't necessarily know if the throne is inlaid with real gold or not in the middle of fighting the undead horde. Sure if he wants to spend several round investigating that while being killed, fine.
Now all this is easier said that done (god knows I break these way too often), but it's still a good thing to keep in mind. If necessary use stopwatches to find out what exactly is causing so much time and evaluate steps to speed things up. Good luck and GG!