All I can give you is some names and sites. Gabriele Nebe co-owns the Lattices site with Sloane, http://www.math.rwth-aachen.de/~Gabriele.Nebe/ and http://www.math.rwth-aachen.de/~Gabriele.Nebe/LATTICES/ and has some work of her own on high-dimensional lattices. She gave a very positive review of a book by Jacques Martinet, Perfect Lattices in Euclidean Spaces. Finally, you might look through every publication by Daniel Allcock, he was the most helpful to me on my final covering radius question, http://www.ma.utexas.edu/users/allcock/