You seem to be describing a rather tired club Allan and turning it into simply a venue for booked acts is going to turn it into just that - a venue for booked acts.
I tend to go with those who object to increasing the number of guests - if there isn't local talent enough to run a club, fair enough, but you will end up not having a club.
Developing a reliable team of residents as always been the secret wherever we were involved - it takes imagination and work.
Wherever we had a club we had a workshop run by seasoned performers to help and encourage newer singers.
We had separate non club nights where performers could work on accompaniments and again, give help to those less experienced
We developed archives of contributed material to be dipped into for building repertoires.
One of the ways we encouraged residents to add material to their repertoires was to establish a practice of singers being asked not to repeat the same songs over a set period - three months worked for us, but that would depend on the size of existing repertoires.
We encouraged projects, such as researching local songs - nights of those could be a draw to non-involved local people if advertised properly, especially in small towns.
Feature evenings of these, along with poetry and prose readings can make for great nights if done with a degree of ability.   
Feature evenings of any sort can be a great incentive to look out new songs on specific themes - Battle of the Sexes, Gone for a Soldier, Go to Sea No more.... loads of themes to think about
Even within an ordinary evening, having themed spots can work wonders.
One of the great audience-catchers for us was the 'You name it, we'll sing it' nights - audiences being asked for subjects of songs rather than specific titles - still remember the feller who passed up a slip which read "Unpaid brickie goes ape and slaughters family" - he was 'hinting' at Lamkin - magic nights, but needing work and dedication to pull them off.
For us, guest evenings were never a necessity, they were the icing on the cake.
You should onl;y book guest because you want them, not because you need them
Jim Carroll