Just to mention a few methods, you can do any or a combination of all of the following... Lightly layer a solo violin with the section strings for the first violins... use a slight amount of EQ and/or filtering on either the first or second violins (you can do a great deal of experimentation with this in order to come up with a sound that you like)... Use different reverbs or room simulation IR's on the different sections and also bus more reverb signal to the second violins in order to set them back a bit more in the mix. The more Impulse Response programs, such as having both Altiverb and Space Designer, plus having a large assortment of IR's to choose from in your pallet to work with, the more creative you can become. Some of the very best third party IR's to consider for orchestral, classical, film, and all acoustic music genres in general are the Pure Space IR's from Numerical Sound.. www.numericalsound.com Here is a link to a piano, acoustic bass, acoustic archtop jazz guitar, and drums, jazz demo that I produced using one of the Numerical Sound "Pure Space" IR's, which also features Bardstown Audio sampled instruments as well..
http://www.bardstownaudio.com/mp3/friends.mp3I recommend having both Space Designer and Altiverb for Logic, because the same IR's in both of these programs do sound different. Altiverb has a slightly darker and thicker coloration of sound, while Space Designer is more transparent. This is not to say that one is better than the other. It is very useful to have as many of these quality Room Simulation programs as possible in order to provide different sounding options, in addition to having a quality assortment of IR's to load into these Room Simulation plugins.
Logic's Channel EQ is an excellent EQ/filter plugin to work with. The Sony Oxford EQ's are excellent as well... www.sonyplugins.com Channel EQ and the Sony Oxford EQ's are both transparent and with a very musical character. There again it is good to have both of these EQ/filter plugins as well, in order to give you more options to work with. Also, the Sony Oxford Inflator plugin for a "tube warming effect" is very useful for acoustic instrument tracks as well. You definitely want to use Inflator in moderation because a slight amount of this "tube warming effect" will go a long ways. Too much of this effect would not be desirable.
With the various tools and methods mentioned above, you can go a very long ways in order to achieve the variety of sounds you are wanting.
Kip McGinnis