When is the activity coefficient greater than 1?
The classic case of having activity coefficient greater than 1 is the solution of very hydrophobic organic solvents in water. For example, if you have toluene or benzene in water, these molecules do not prefer to stay in water. This type of work was a popular research topic in the 50-70s.
Note that here we are talking about neutral solution so the concept of ordered lining up does not arise.
There are plenty of papers on this topic. Just search activity coefficient of benzene in aqueous solutions.