If I had to base all work on one fpga all-in-one board I think Enterpoint's Darnaw1 would be suitable. Its small, it can be used on 2 layer boards with 110 I/Os and on a 4 layer board 219, it has a 1200k gate Xilinx fpga and some RAM. No unwanted extras really. Initially you would have to make a 'motherboard' to plug it into with CPU, SRAM and PIC and regular ports but over time you can cut it down to just the ports, the rest is on the fpga.
1.2M gates should be well and truly enough space for whatever we can come up with - The main issue is price.
