@kheredia : Without more specific info, you are best off going to a local garden center and see what they are selling. California (very long from N to S) covers many gardening zones. Annuals bloom all summer but have to be replanted yearly; perennials cost more and need more care when planting, but will hang around.
Some flowers need alkaline soil and some acid; different plants have different watering requirements; different colors either clash or mesh, height matters. Your garden center can draw you a plan; or get a flower book from your book store; it will have ideas and various plans in it.
(And didn’t you tell us that your larger dog will eat anything? Animal, vegetable or mineral? Aromatics like mint, lavender, bee balm, lemon balm, basil smell nice when crushed or trampled.
Cosmos and cleomes are easy and tall and like sun; impatiens are easy and very short and require shade.
Gardening (including the mistakes…sometimes I think I should skip the middle man and simply plant money) is a very satisfying hobby.
CA gardening zones range from 7 to 24. http://www.sunset.com/garden/climate-zones/sunset-climate-zones-california-nevada-00400000036331/
I live in low hill country in the NYS snow belt and I am zone 4B.