As a fellow GM of Rise of the Runelords and an author on Ultimate Intrigue, Intrigue's value to you in Runelords is going to depend on your GMing style and your group's play style. Do you like to add sidequests or extra depth to what's written in the AP (like how some GMs, including me, added a trial in between part 1 and part 2, or many GMs use the Sandpoint gazetteer in the back to create more interactions with the various factions in Sandpoint)? Are your players likely to play up becoming lords of Fort Rannick after Part 3, and if so, are you looking to create more content for them in that vein? If the answer to any of those is yes, then Intrigue has some pretty darn useful stuff. Even if not, the Spells of Intrigue section is going to be useful for considering the sorts of divinations the party might use, since Runelords has several mysteries, and you could easily turn the library in Part 4 into the library rules.
I'd also consider if you've started yet or not.
If not incorporating additional rules/stuff is much easier and can be much better planned to look "organic".
There's a lot to be done with the five ruling families of Sandpoint and the Szarni present in town.
Possible interludes between #1-#2-#3 come to my mind. Fort Rannick certainly is another fantastic opportunity for both, UC and UI!
Really like the idea of using the library rules for #4--thanks!
As Mark said, I'd also have a look at the play style: do you (and you players) need more codified rules or are you happy with roleplaying-acting these kind of things?
Ruyan.
As a fellow GM of Rise of the Runelords and an author on Ultimate Intrigue, Intrigue's value to you in Runelords is going to depend on your GMing style and your group's play style.
Mark has made the right call. So much depends on how you plan to pace the campaign and how much emphasis you want to put on the intrigue side. As things stand, there are only a few opportunities to use intrigue in RotRL, since so much of the action takes place off in the wilderness, far away from civilization.
We started our current RotRL campaign long before UI was released. When players first went to Magnimar, I homebrewed a fair amount of additional content which required frequent uses of diplomacy and intrigue to work with the city council, the mayor, the captain of the guard and various merchants while they were working against Ironbriar and his secret patron. We didn't have UI available at that time, so we used the Social Combat deck (in a homebrewed method, where each character drew a number of cards based on his CHA score).
Now they have just finished with Fort Rannick, and in upcoming adventures the party will be returning to defend Sandpoint and to cash in their diplomatic chips in Magnimar. Since Ironbriar died, but his secret patron got away, they will find a hot diplomatic situation to deal with back in Magnimar, since that secret patron has been busy in the party's absence.
We will be using the Influence system, Social Conflicts, as well as a full-blown Verbal Duel in the Magnimar council chambers, as the players try to out-diplomacy the secret patron's newest lackey. One word of warning, though: the Verbal Duel system is quite complex and requires a fair bit of extra work on the DM's part to help the players get into it, without geting dragged down by minutia. I'm preparing several reference sheets to make this situation run more smoothly.
Once we get past that Verbal Duel scene, there will be very few opportunities for social combat of any sort in the rest of the campaign. Assuming players stay more or less on the campaign railroad.
OTOH, if you go full-sandbox style with the players becoming Lords of Fort Rannick and building their new "kingdom", you could easily work in numerous additional opportunities for additional diplomacy-based situations - negociating with neighboring communities, defusing potential aggression from Korvosa and so on. If they really like that sort of thing, you might even never get round to the subsequent books of the campaign.
Edit: also, the sections on "spells of intrigue" are golden. Lots of issues that regularly come up on these boards are dealt with there. Great stuff!
Social Combat and Verbal Duel both needs some tables or flow charts so they can be easily explained to players.
What Verbal Duels really need is a new set of Social Combat cards designed to work with that system. My players liked the way we used the social combat deck, but doing a Verbal Duel with 10 optional strategies for each exchange is going to be challenging. Especially since I'll need to translate it all into French for my players. <g>