First things first:
DON'T GET RID OF THE TREE!
Seriously, that is a FINE looking specimen that some pay thousands of $$$ for to get the same look in their garden. An absolute stunner!
I'd start with underplanting that area. Am I right to conclude it's largely south facing? If so, that combined with the tree casting shade later in the year gives you alot of options.
1 or 3 (odd numbers are more pleasing to the eye) of the same-ish shrub to add more bulk, texture and interest could be a start. Think Azalea and Rhodies if you have acidic soil, Fothergilla, more hydrangeas...
Underplanted with woodland plants combined with some that need a little more sun at the front.
Anything you like. Experiment.
JUST DON'T CUT THE TREE!
If your budget is limited (or non existent), look around online for people offering divisions at a low cost or grow from seed. You can get alot of plants out of a small and cheap packet.
