You probably need to give more information before getting suggestions back. I'm finding it difficult to picture where things are - could you post a picture, especially one taken from an upper floor window to give the general layout? Also, what kind are your established trees? How shady is the area you are looking at? Your layout and the kinds of trees will influence what new plants can be grown there, since often root competition from trees can be quite severe. For others reading this, and for you before you remove your azaleas, in areas with established trees, rejuvenation pruning for many kinds of shrubs and hedge plants may be more effective than trying to establish new shrubs in an area with much root competition.

You can do a search both of this forum and on Google for narrow, columnar, or fastigiate shrubs to get suggestions for plants that grow in the shape you want. Likewise, search for evergreen hedge plants.

I can't suggest specific shrubs for you since my zone is so different from yours, but in addition to shrubs, consider vines grown on some kind of a trellis or lattice or even large gauge wire fencing fastened to the split rail fence. Around here clematis or some of the non-invasive honeysuckles can grow quite thickly even though they are deciduous, and the trellis itself can provide some screening. Climbing roses (not really a vine, but can be trained to a trellis or your fence) might also suit your purposes, though when the leaves are gone they are not good screens, so you'd need to plan the trellis to provide the screening or use it in conjunction with evergreen plants. Clumping bamboos (not running bamboos) and tall grasses can also provide screening in a relatively narrow format, though the grass would need to be cut to the ground in early spring and leave you without screening for a few weeks while it regrew.

I will not be able to post a picture, sorry. There is a tulip tree along the fence, then an area about 10 - 12 feet, and a pine tree. The tree we took down was next to the tulip tree. So I would need to place something in between and in front of those trees. My first plan was to move the azaleas back, but I may be better off starting with smaller azaleas. I also thought of a smaller viburnum, or maybe an oak leaf hydrangea, like snow flake, although deciduous. I can raise the bed as well, as erosion has removed some of the soil over the years, as I pulled out all the English ivy.

More dwarf varieties of Holly, camellias, dwarf variety rhododendrons...??

How much sun does the area get and is it morning or afternoon sun (or both)?

Viburnum pragense 'Decker' is evergreen and is supposed to have nicer flowers that the commoner pragense. Mine is new and has not bloomed for me, yet. I am using it, instead of the commoner V. Rhitidophylum (sp?)because the latter has sadly hanging leaves most of the Winter.

Depending on your sun exposure, here are some possibilities: Camellia japonica (need shade), Camellia sasanqua (tolerate full sun), gardenias (won't tolerate tree root competition, but need shade), azaleas (Encores tolerate full sun well), Nandinas, loropetalum, Illicium (likes shade at its feet, sun on its head), Danae (shade. No flowers but beautiful berries. Truly beautiful.), Pieris, Mahonia.

Fragrant tea olive. It's hardy in my zone with a little scorching with the very first frost. They're slow growers, but the smell is amazing in the spring. They can be hard pruned if needed.

I've got one in full sun. It's grown the fastest. The one in morning sun flowers best.