Assuming the edges are planed accurately straight and square, a simple butt joint will be perfectly adequate and the use of jointing biscuits will not add any extra strength. They will however make the alignment of the panels easier when cramping together. If you are using PVA adhesive, the open time for assemble is quite short, so if the panels are built up from quite a few boards, it would be best to cramp them together in several sub-assemblies to ensure the adhesive does not start to dry and give you a thick weak glue line.
