In england the sow stocks with bulbs-the single types usually red and orange.Violas, fever few,corn flower, larkspur,sweet william,and lychnis overwinter for me in zone 6 Connecticut.Shirley poppies and snaps do come through too but not all of them. You might like verbena bonariensis for spring sowing-it will probably be perennial for you. Cleome is another re-seeding annual that blooms most of the season. Dalias look great here late summer into fall-until the frost:( I grew the gallery types this year and really love them ,especially the red. Its doing great in 1 gallon pots too,still blooming! They might overwinter in the ground there if planted deep and mulched-they do here in places.Another summer blooming annual I like is cosmos cosmic orange or yellow. It stays short.Have you grown schizanthus? It isnt used here much as are godetia,nemesia, and clarkia because it heats up too quickly in the spring. It might work well for you.