We added three grab bars during our remodel when we first moved in, but we've just added four more--two in each bathroom. The first two big grab bars (first remodel) were installed in the shower in the small bathroom--the longest on the long window wall and the shortest on the short wall (the end wall opposite the shower head). These are both horizontal.
The long grab bar in the bathtub/shower in the hall bathroom is angled (my preference); I had that done in my bathtub/shower at the old house that we built. That gives you a better choice for grabbing.
The new grab bars were added at the advice of a nurse for a family member--except for the one in the tub/shower which had been thought about for some time; it's just inside the corner to use getting in and out. Now there are two short vertical grab bars in front of the toilet in the small bathroom. They're under the towel bar and above the toilet paper holder. They fit nicely and aren't too obtrusive.
A longer grab bar--also vertical--is next to (actually in front of) the toilet in the hall (bigger) bathroom--in case that bathroom is needed in the future... The long grab bar is 18" and brushed stainless steel. The three short grab bars are each 9" and satin nickel--much more elegant than the long ones, which actually look pretty good too. They work together, and we're grateful to have that project done now.