How wonderful to have a lot of room to play with. :-)

I like to plant (stuff is a better description) bulbs between perennials and shrubs. There are a lot of squirrels here and they love to dig up anything newly planted. What I do is placing chicken wire over the areas holding it down with bricks or rock until the soil settles.

Blood meal also works well to deter squirrels and rabbits.

I love all kinds of bulbs scattered througout the garden among perennials & shrubs. I don't match anything at all. The garden looks stiff when things are planted symmetrically.

I would plant bulbs and perennials by your Viburnum. Plant a small Clematis or two to grow through Viburnum too, since Viburnum gives you blooms only in early spring.

I have different bulbs/corms/tubers that give me blooms beginning in Feb/March until late October/ November in the following order, if my memory does not fail me:

-Galanthus
-Eranthis
-Iris reticulata
-Crocus
-Species Tulips
-Early-Mid-Late Narcissi
-Early - Mid - Late Tulip
-Leucojum aestivum

These minor bulbs bloom about the same time as Narcissi & Tulips:
-Schilla sibirica
-Puschkinia
-Species tulips
-Chionodoxa

Late spring:
-Allium
-Iris
-Gladiolus bizantinus

Summer:
-Lilies -Asiatic -Longiflorum/Asiatic-Trumpet/Species/Oriental-Orientpet-Species
-Liatris spicata

Late summer/early fall:
-Fall Crocus
-Colchicum

I also have been growing some Dahlias these past few years. This infatuation with Dahlia might not last long, because I rather hate its winter care.
And I also have a clump of Canna that might meet the same fate as Dahlia.

There are many choices of bulbs to satisfy you. I don't think I have listed all of those in my garden.

About the sun/shade issue - if you have deciduous shade, lots of minor bulbs will bloom and die back before the trees leaf out. I grow Scilla Siberica, Ipheon, Chionodoxa, Fritillaria Meleagris & many others including Tete a Tete (small daffodils), under low branched Crabapple trees. They get enough sun to bloom just fine and multiply. So you may be able to carry more bulbs from one side to the other than you think.

As for the design issues you mentioned, I have often made new beds in the fall, planted them with bulbs and mulched them, and then added perennials the next spring. One trick I have learned is that if, and it's a big if, you know the basic layout of the bed, you can plant empty upside down nursery pots into the bed, where they major players are going to be. Push the upside pots deep into the soil and then plant your bulbs around them. I usually leave enough room bare around the pots so that I can easily work with a shovel when planting the perennials in the spring.

You can also stake out large areas for large plants or shrubs. You can even get fancy and use a different color or kind of mulch to remind you where things are or are going to be. Just make sure to trail the bulbs around these spaces in a meandering way so that things look natural. You don't want exact circles around each pot!

To be honest, when it comes to inexpensive minor bulbs that can be bought in the hundreds from Van Engelen, I just sheet plant them in fall and plant my perennials right in the middle of them in spring. Any that get dug up by the shovel/trowel just get replanted around the crown of the plant.

As for designing on both sides of a walkway, I think this can be pretty flexible. It is nice to use some of the same things on both sides along the pathway for continuity & repetition. But not every plant or bulb can or needs to grow everywhere.

You do not have to be rigid in your layout about heights. You of course do not want to plant tall bulbs blocking shorter ones, but the perennials in the bed will be mostly invisible when the bulbs come out in early spring, and most won't be large even at the end of spring bulb season.

When it comes to later bulbs, it is a bit more complicated. The big alliums look great towering over perennials. Their foliage is often so bad you need the perennials hiding it even before bloom, but afterwards the foliage disappears quickly often leaving some wonderful drying flower heads. Daffodils (full size ones) need something like daylily or sedge foliage to hide its dying foliage. Either that or plant them out in the distance - or the foliage will drive you nuts! Or use miniatures - wonderful color in a small package. Lilies often get very tall and look nice planted around good sized perennials that hide their long stalks. Their foliage is persistent and you can have different types of lilies growing from early to late in the season. The foliage on my late bloomers lasts till frost. Siting lilies can be tricky and although I love them, I am often not happy about their locations by the end of the season!

Also keep in mind that very small delicate flowers, need to be seen up close, but you can play around with perspective a bit by planting little flowers in the distance to make things look bigger - or tempt people down a path. On the other hand if you sheet plant small bulbs, they look great from a distance. I like to make fairly wide ribbons of all blue bulbs (many varieties, blooming over a long time from early to late spring) with smaller spots of white, yellow and pink. You could also pick a different color, or one kind of bulb, and run it through the whole bed, accenting it with other colors or bulbs. Just because I am fundamentally incapable LOL of one color or one variety doesn't mean you have to be - there are lots of options.

Tulips being poor rebloomers are another issue altogether. I use 2 methods, small clumps here and there of reasonably good returners, near perennial(s) which will make me forget about them by summer and forgot where I planted them in fall and a dedicated space where I treat them as annuals and plant over with annuals in early summer. That way I always have one really good tulip show in spring and a few surprises here and there.

Best wishes, Leslie