When I do one-shots with new people, I make pregens based on exciting fantasy portraits I find online. That way, they can just pick the picture they like best, and what you see is what you get.
Since your new group has experience with playing RPGs, I would NOT do pregens; I would simply tell them that they need to come with a finished character - tell them to do point buy or rolls, and whatever else.
This is such a great idea!
'Oh yeah sorry, I didn't get round to making a character in the 2 weeks between us deciding to do this and today, I'll just make one quickly now.' *Proceeds to spend the next 40 minutes making a character and the 20 minutes after that making adjustments.
I can guarantee that if you don't do pregens, between 1 and all of your players will do this...

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.