IMO there are four methods to visualize this, each of 'em has it's advantages and would give nice choices to the players. IMO it would be kewl to feature all but since it's a development thing for now as a viewer of it I'm happy with the current thing – I only would change a little at it. See this graph:
* = has nothing to say at all, just a type formating helper
>-----> = Ship no shields
Sci-fi 1:
*____
/****\
>----->
\____/
^^ the sci-fi bubble, known from tv series
Sci-fi 2:
_________
| >-----> | = the current thing
-----------
^^ the around the ship thing, only one inch above ships hull
In-between-things (my favorite):
**--
>----->
**--
^^ like the torus, matching development with non-sci-fi the easiest way. Means a cutted mesh (e.g. the middle of it). IMO this would be a good solution. Fading out horizontaly at both ends is IMO possible. /edit: BUT cutting a mesh can be tricky /
Note: this method tries to reproduce the following...
Non-sci-fi:
>--0-->
^^ the realistic torus, in middle or where the crew is at. Could be made with two generic torus meshes (CapShip or Delta Glider size or maybe more just saying).
//edit: By randomly surfin the web I found this ...is this any interesting speaking about the real non-sci-fi specs? To me at least the images were interesting pointing to non-torus magnetic field visuals, afaik earths magnetic field is round because our lil' magnetic core is round. This means: figure "in-between-things" is suggested to be applied.
http://www.google.de/imgres?start=67&sa=X&espv=210&es_sm=93&biw=1612&bih=934&tbm=isch&tbnid=a4doHnQatb_DPM:&imgrefurl=http://iopscience.iop.org/1367-2630/10/12/125007/fulltext&docid=xRL4EyTy3nzGjM&imgurl=http://ej.iop.org/images/1367-2630/10/12/125007/Full/nj278928fig3.jpg&w=573&h=251&ei=7F6nUr2KFvHe7AaMoYGYCQ&zoom=1&iact=hc&vpx=526&vpy=140&dur=546&hovh=147&hovw=338&tx=207&ty=112&page=2&tbnh=136&tbnw=259&ndsp=79&ved=1t:429,r:27,s:100,i:85
///edit: needed to edit one thing on the topic "torus", I descibed them as spheres which was wrong for sure.