I am on the same side as Karen, I do not offer extended stay discounts. How I look at it is, you are still giving their pet the same amount of love, attention and care as you would on day one as you would on day 20. (and truthfully, I think the longer they stay the more you fall in love with them so really you probably give them more love and affection. lol)
In all fairness you still are putting in the same amount of time and work, so discounting the price honestly does not really make a lot of sense to me personally.
What you do also want to take into consideration is that you do not get paid until after the reservation is completed. You may want to break the reservation up into 2 weeks at a time so you get paid in a timely manor.
but keep in mind if you do decide to offer a discount then you may run into some issues if her house is done way before expected. (depending on what day you decided to do an extended stay on, lets say her house is done before that date. Are than going to adjust the cost back to the original price?)
I think that you are just asking for problems when you start offering discounts and you open the door for clients to try and take advantage of you that way.
(Example lets say you offer clients a discount if their pet says 15 days or more. You than have that client that has 2 pets who stay 14 days and wants to know why they can't have a discount also, its only 1 day or a couple of days and so on.
You just open yourself up for too many problems once you start offering discounts. You have to price yourself out for what you think you are worth.
I think that your prices are low as it is. I don't know what other sitters in your area are charging but your prices are very low as it is. (I am in San Diego so maybe our prices are just overall higher??) Right now you are only charging them $40 a day for 2 dogs (that is $20 a day) I know in here in San Diego there is no where that you can board two large dogs for that price, plus not to mention all the benefits that the dogs will get being in your home vs a kennel. (your yard alone is big and beautiful... a puppies paradise!)
At the end of the day, it is what ever you feel comfortable with. Best of Luck!
Erica
P.S. Not sure if you realized it but I think you House sitting holiday charge is wrong... you have it at $28. just thought I would bring it to your attention.
Take care and best of Luck!!