Raised beds with Sleepers

Hi,

In my new garden I have aroughly 3.6m by 4.6m area that I want to put some raised beds in.  The wife is insisting that it can't look scrappy so am going down the sleepers route.

Any advice on what sie to make the beds?  I have 1.2 x 2.4 beds on allotment and although that is fine I would prefer a bigger bed, but not so big that I can use it all or have to alk on it?

Garden is east to west.

We built some last year and followed the advice of our friend who helped us- they are one sleep long, and half a sleeper deep,as minimised numbers of cuts and meant no wood wasted, we have 2 beds next to each other 'end to end'  only downside is they are against the fence- and does mean their is a 'hard to reach bit', but does mean they are helping yo support the neighbours fence!
The sleepers are on their ends, and 2 sleepers deep is a good depth- nice height to sit on with a glass of wine!