Adam Hastings and Fergus Burke will provide competition and cover for star fly-half Finn Russell.
Ben White and George Horne are the scrum-halves, with Jamie Dobie an option at number nine but thriving on the wing for Glasgow Warriors.
Captain Sione Tuipulotu is joined by Glasgow team-mates Jones and Stafford McDowall and Northampton Saints’ Rory Hutchinson as the specialist centres.
The back three selection will come from Blair Kinghorn, Tom Jordan, Kyle Rowe and Ollie Smith, who are all options at full-back, along with Duhan van der Merwe, Darcy Graham, Kyle Steyn and Dobie.
McConnell, 21, and Douglas, 20, each have one cap and join Magnus Bradbury, Jamie Ritchie, Josh Bayliss and Glasgow trio Matt Fagerson, Rory Darge and Jack Dempsey in the scrap for back-row places.
There are three loosehead props; Pierre Schoeman, Rory Sutherland and Nathan McBeth, with Elliot Millar Mills and D’arcy Rae supporting standout tighthead Zander Fagerson.
Scotland open the tournament in Rome on 7 February, then host England before a trip to Cardiff on three successive Saturdays.
France visit Murrayfield on 7 March and Scotland are in Dublin for the final round of fixtures seven days later.
“I’m sure we’ll be rotating our squad at some point,” said Townsend. “Whether that means within our 23 and changing things up or bringing people out with your 23.
“You just never know about injuries. They’re surely going to come when you play three Test matches in a row.
“I actually think it suits us and maybe Italy because in the past there were two fallow weeks and teams trained during those fallow weeks, but we’ve not been able to do that because we’ve had a lot of players playing in England and France and they’ve been going back to play for their clubs.
“Only having one week, I don’t think many teams will be training. They’ll be using that as a recovery week. Most teams are back on a level playing field for this championship.”
Scotland finished fourth last year, with third place in 2023 and 2018 their best showings in Townsend’s eight previous attempts.