Most efficient way to lease out a commercial space

[Russell A langkawel]

My family and i have owned a 20,000 sq ft strip center for about eight years that we purchased in foreclosure. It consists of eight x 1600 sq ft spaces and one x 4350 sq ft space. When we purchased it, most of the smaller spaces were empty (the large one was leased) and over the first three years, we leased out the entire center. Over the years we have lost and re-leased a few of the the smaller spaces with pretty good success using signage/ other local real estate agents etc (it is in a desirable area so it has been pretty easy). Twice we tried listing the spaces with local commercial agents, but both times it seems like they got the space under contract, put a sign out front, and did nothing else.  Recently we lost our large tenant and have gotten ZERO inquiries about this space. I would really like to get a decent national tenant for the space, and I don't mind paying out for it if I can get a stable tenant, good rent rate, and long term. What do you pro's recommend I do?