I want a pretty front slope like this

This weekend my mom and Rich are coming over to help me get started cleaning up the yard (aftermath of sewer and drainage work). If we have time, we also may try to start planting on the slope in front of the house (where the Juniper bushes used to be). On Claire's recommendation, I've been looking at yards in my neighborhood for the last couple of months to figure out what I liked. I did this while walking Maple and would take pictures. To help my mom and Rich understand what appeals to me I posted a bunch of these photos online for them to peruse. The one above is from my favorite yard so far. It's a really nice mix of flowers and greens planted tightly together in a naturalistic fashion. I think that's what I'm going to go for. I have to talk to Benjamin first, but I think it would be cool to rip out some more of our existing plants that I don't like - the holly bush, the "boxy" hedges in front, and maybe the bush and tree with red berries (but probably only if they're toxic). My other thoughts on what I would like in front of the house are:

• I like the “natural” rocks that come in various midrange sizes and shapes (not smoothed or squared), but I'm thinking I won't make any formal tiers since I like the natural look
• I like dense planting so no weeds have room to grow!
• I like a mixture of flowers and green things (grasses, bushes, and so on)
• I want perennials
• I want things that bloom at various times of year to maximize colorful months :-)

The slope we're planting gets full sun and has western exposure. We also have an area at the back of our yard that I want to turn into a flower bed someday and it gets partial sun. If anyone has ideas on plants I should try, techniques, or other landscaping thoughts, pour them on now!