I am all about multiple seasons of interest…ask before buying a plant how many weeks of joy in how many seasons it will give. Mock orange can get twiggy and messy, with some dieback. The best ones have unbelievable fragrance for a week or so in spring…but is that enough? Hmmm… Therefore many of the best Viburnums (spring flowers, summer or fall fruit, colorful fall foliage) will get more points in my book than even lilacs (which are great for a couple of weeks and then dull I think…though I have many!). A bonus: fruiting shrubs like viburnums will also attract birds. Make sure you have the right mix of plants for good fruit set, if fruiting shrubs are of interest; your nursery should know what you need. Instead of privet, what about some of the little-leaf hollies…inkberry (Ilex glabra), for instance? Ask your local nursery if they are hardy for you; they are rated Zone 4 or 5, but windy winter conditions can cause damage, I think. But ask…local growers will know best. If the evergreen hollies don’t do well there, deciduous winterberry holly (Ilex verticillata), which drops its leaves but gets amazing red, orange or gold fruit, is perhaps one of my top 2 or 3 woody plants ever. They don’t look like much in summer, just green (which is all your privet would have been), but when those leaves drop in October and into perhaps late January (by that time the birds have picked it clean), wow! I have created some large plantings like this with only hollies and viburnums and never regretted it…in some cases, the beds have 20 or 30 plants, a giant haze of color all fall and winter, like a big bird feeder. Aronia arbutifolia, or chokeberry, either the red-fruited ones or the blue-black fruited kind, are great in such a bed, too. Now of course I started by saying multiple seasons from every plant, and the winterberry hollies aren’t that. A mix of your lilacs (for spring), some great viburnums (for spring-summer-fall) and winterberry hollies (fall-winter) would be nice, and you can add a few extra things at the foreground for summer enjopyment if you like, when you’re sitting out there.