Some cats can be very happy indoors. You could get 2 kittens and at least when you weren't home they would have company and it would help stop boredom!

Other things to consider is:

Window sills free so they can watch the world go by.
Cat scratchers and climbers
2 litter trays in different areas
Food and water in a few areas (this gives them a chance ''to seek out food'' and encourages more drinking)
Plenty toys that are rotated regulary to keep interest
Puzzle balls and feeders
Places and items for them to sleep in and on
Also you will have to make plenty of time for playing with them Things like rod toys, cat lasers, and lots of cuddles!

These are some things of the top of my head when i kept my 4 cats in. Good luck in your quest for cats! Please keep us updated!

__________________
LOADING CRAZINESS..
████████████]
99% complete..

(-: plɹoʍ ʎʌɹnʇ ʎsdoʇ ʎɯ uı uo ƃuıoƃ ɥɔnɯ os 'uoos ǝɯıʇʎuɐ ʞɔɐq ǝq ll,ı ɟı ʍouʞ ʇ,uop 'ʞɐǝɹq pǝpuǝʇxǝ uɐ ƃuıʞɐʇ ɯɐ ı