Question
I am tearing out overgrown (25 years old 8 to 10 ft. across) junipers from a 90 ft. area of my front yard. The front is two tiered (rock wall three ft. high separates the front). Lower area is 90x36. Upper is 90x24. The junipers are woody and are across the top of the rock wall and take up about 40% of the area below the wall. They face north and receive ~ 4-6 hours of afternoon sun.  My intention is to sod the lower front with a sculpted area for possibly some Endless Summer hydrangeas. Since the area is now totally covered by the junipers, I wondering whether the area will look too sparse. In addition I'd like to know if this variety of plant is a good choice. Recommendations?"

Answer
It is a fine thing to fall in love with a single plant, but in order to display it for optimum enjoyment, your Hydrangeas needs 揷ontext?  Even the best of deserts make a lousy breakfast-lunch-dinner menu if that is all there is to enjoy.  I agree that too much(plus old & leggy) juniper is a bad thing, so out they come.  

Here is an article that discusses 揻oundation?plantings, which is similar to the 90?wide wall/tier arrangement you describe:
http://www.thisoldhouse.com/toh/article/0,,1592703,00.html

As far as 揺ndless summer?hydrangeas, they are deciduous, so for several months out of the year, they will just be brown twigs sticking out of the ground.  

Like a good jeweler displaying his diamonds, you抣l need a backdrop of velvet (in this case a 揼reen?velvet of other more mundane plants) to make the Hydrangea抯 beauty stand out...So yes, replacing the juniper with just lawn & hydrangea alone would be too sparse.  

I抎 even mix hydrangea varieties, if you are so inclined.  There are lots to choose from:   http://www.hydrangeashydrangeas.com/

You didn抰 mention what part of the U.S. you are in.  Now the acidic soil from the removed juniper area will give you awesome Hydrangea bloom colors.  However, that isn抰 the only challenge for this Southern plant:  Here is discussion about growing this warm-loving Hydrangeas in a colder climate:
http://www.coldclimategardening.com/2008/06/01/forever-and-ever-hydrangeas-takin...

Hope this info helped a little. ~Marc