Sounds like a wonderful start .. but if you are building from scratch . .

wide and deep to me means that the open side is the width .. the 11'

Under those circumstances ..

.. I would fill the 11' side with the banquette end to end and not do banquette on the sides .. . .here's why . . you can then play with different shaped tables over time . . start with a six foot pedestal oblong table to seat 6 - 8 and you have room to put taller / fancier /better looking / feeling chairs at the ends and still pull them out .. with more casual chairs facing the banquette. . .. over the years, you might go to a round 42" table set about 1/3 of the way along . . great for four or even five ..having tea, toast or tablet .. .and the rest of the banquette gets to be a sofa for the kitchen .. the table is more fun for homework, etc. . 11 is not really long enough for a 10' table unless no one sits at the ends (more people is usually why you need a longer table .. but is sort of awkwardly small for 8' if you do any side banquette / corner at all (which is a VERY large table) unless you only use the 8' at holidays and you select an oval so the ends are softened some . . if you put banquette on both ends it is too big for a six foot table, but if you put it on only one side . . . it will work ..

How many people will you seat daily? Are you envisioning the L due to the layout of the rest of the room? If it is a long table it is easier to set it right for just one fixed point than for two ... and extra banquette that goes beyond the table makes it easier to get in and out .. think about your favorite banquette restaurant .. walk up, sit down, scootch over . .

banquette seats are 18" deep plus another 4-6" for the cushioned back / frame . 2' or so .. (look at ballard.com for exact dimensions - they sell them in sections) . .but the table needs to come over the seat for comfortable eating ... so you envision the table itself overlapping some distance .. 10" or so . .