My idea is a bit ambitious, but I'd like to see a major expansion, called something like Country Life. I'm an Iowa girl; so, it kind of makes sense to me. These would be the features.
Older style houses (Victorians and Four-squares), plus barns. Players would have the option of building their own home initially, but barns are set pieces (explanation below).
At the outset, players decide whether they want to be dairy farmers, horse ranchers, or raise poultry. Style of barn will depend on this initial decision. At the onset, barns are limited in size -- four cows/horses or a dozen chickens.
Dairy farmers derive their income from milking, selling calves, and from breeding fees (if they opt for a bull).
Horse ranchers derive their income from selling colts/fillies, breeding fees (if they opt for a stallion), and from boarding other Sim's horses.
Poultry farmers derive income from selling eggs and hens/roosters.
As the livestock remains in the barn, there's no need for massive lots, and animal animations are minimal, with only the occasional head poking over a stall door or a hen roosting when a Sim collects eggs. Livestock sounds do abound, and if the Sims don't clean stalls or tidy the chicken barn nasty odors become a mood killer.
Appreciation of livestock value/produce is much like gardening, where players are able to breed their stock to higher quality animals, thus producing better offspring, which will fetch higher selling prices and/or better milk/egg yields. Players not opting to have bulls/stallions/roosters in their limited barn space will have the option of paying for breeding -- at a premium fee, of course.
Overhead will also be factored in -- feed for each head of livestock will be charged, much as bills come in the mailbox currently. When they can afford to do so, players can expand their barns with stock they've raised, or they may purchase new stock. Each new head of stock will result in a higher monthly feed bill, which will cause some amount of decisionmaking.
As in real farming, not everything is predictable. Dairy cows go dry prematurely, are sometimes barren, and calves are sometimes stillborn. And prizewinning bulls/stallions/roosters don't generate better get every time. Also, livestock can get sick, especially if they're not fed regularly or are forced to live in filthy confines.
If a farm has a run of bad luck it's possible the bank will foreclose. Farming Sims and their spouses may have to go to work outside the farm or sell off stock to retain the farm/ranch.
Two special features will be added -- auctions and country fairs. Auctions will provide farmers an opportunity to purchase prize stock and to perhaps sell their own stock at a higher price than merely clicking the sell button. Country fairs provide an opportunity for farmers to compete in livestock shows, where winning or placing well will increase the value of those animals exhibited. The country fair will also feature a midway, where players can try their hands at the ubiquitous fair booths -- balloon popping, shooting gallery, and ring toss. Gardening Sims can also enter their produce for competition, and good-cooking Sims can enter the best-cake competition.
And speaking of gardening and cooking -- this is another outlet for those ambitions. There might even be a talent contest for musicians, as well as photography, painting, and sculpting competitions. These are certainly in keeping with venues found at many contemporary fairs. There is also a barn dance at the fair, where Sims have an opportunity to meet others socially, go on a date, or continue courting their chosen mate.
As for the dovetail with World Adventures, players will have the opportunity to search for livestock in France, China, and Egypt. If they can afford to ship the respective animal(s) home, they have an excellent chance to improve their current bloodlines or introduce a new breed altogether.
One last feature is the farmhand. Much like the butler, the farmhand can feed stock, milk, collect eggs, and clean stalls. The farmhand lives onsite and gets about $1200 weekly. Players may also opt for a veterinarian to check on their stock regularly (for a fee of course). The vet will minimize the likelihood of sick animals and stillbirths.
I think that about covers my thoughts; as I said, it's ambitious, but I think it's very doable; moreover, I think such an expansion would be extremely educational and will cause some serious decisionmaking and no small amount of risktaking.