The GPC suggests that, in 496 AD, those knights who contribute to the building of the wall around Sarum (the town AND castle) should be bestowed with gifts, titles and other rewards. Everyone of my PK contributed, some even contributed a lot earning Generous checks. I'm looking for suggestions about what these rewards and titles and gifts should be.

The GPC suggests that, in 496 AD, those knights who contribute to the building of the wall around Sarum (the town AND castle) should be bestowed with gifts, titles and other rewards. Everyone of my PK contributed, some even contributed a lot earning Generous checks. I'm looking for suggestions about what these rewards and titles and gifts should be.

another warhorse, some land as a Gift, elevation to be officer of the household, a small boon/favor granted, jewelry

In our campaign, the Countess has a sort of proto-parliament of vassal knights, whose advice she seeks in the matters of tribute payments and defense. With the PKs arguing strongly for the necessity of the wall, a small annual 'wall money' was levied for the construction of the walls. Thus, simply contributing that amount would not be anything worthy of extra rewards in our campaign. However, someone contributing well beyond the norm, and significantly so, the Countess would take notice. Something in the £50 range would definitely be the time to give out some gifted land, for example, while something in the £10 range would perhaps make her more inclined to listen to what requests the PK might have (not marriage to an heiress, though, they are more precious!).

In my campaign we took it one step further. In order to preserve unity the PKs took control of Salisbury. They formed a council. One of them was named Chancellor and could speak on behalf of their Lord. The others were granted officers titles. Payment to improve Sarum was part of the deal.
The plus side for me as GM meant that the players were now more in control of what happens in Salisbury. As part of their leadership they were also given control of manors of their extended families that are without a knight. These were gifted to them until the rightful heir is of age. Which in some cases could be more than 15 years. We call that a stewardship of the manor.

If you do not want to go that way. Greg's suggestions are the way I would go.