But with the Grizzlies planning to stay in the lower-level Big Sky Conference, the WAC might eventually invite Seattle University in all sports except football which is how Denver is joining the league, since it doesn't have a football team and doesn't plan to create one.
Only Texas State and Texas-San Antonio are bringing football teams to the WAC.
But Benson said the WAC will continue to look for other prospective new members, in addition to Seattle, though he did not name any. Ideally, he said, the league would include nine teams in football and 10 in all other sports.
"We still have options, and we still have time," he said.
Barring other additions, the new-look WAC figures to feature eight teams in football and nine in men's and women's basketball, starting in 2012-13.
Its three new schools will join San Jose State, New Mexico State, Idaho, Louisiana Tech, Hawaii and the Aggies in a conference that has survived seemingly constant upheaval during the last 15 years. It's possible, though, the new football team from Texas-San Antonio might not play a full league schedule until 2013.
The Roadrunners don't play their first season until next fall under former Miami coach Larry Coker, and both they and Texas State plan to move to the Football Bowl Subdivision level from the lower-level Southland Conference in 2012.
Denver will join from the Sun Belt Conference.
"I've said often that when schools join the WAC, they get better," Benson said. "And over the past 10 years, we have a track record to prove it."
The Aggies praised the expansion, even though they soon will have to travel farther for some of their conference road games.
Football coach Gary Andersen noted the opportunity to increase recruiting in Texas, while men's basketball coach Stew Morrill said "the new additions will prove they belong" and make the WAC stronger.
"These programs have the right plan and have committed resources in place to back them up and be successful in the WAC," athletic director Scott Barnes said. "Collectively, their academic and athletic success is impressive."