You don't see many appellate cases that actually award fees for a party's refusal to admit RFAs. In part that's because very few cases go to trial, and in part that's because trial courts have lots of discretion to find that the denial was 'substantially justified'.
But if you want a case with which to credibly threaten the other side if they say "Deny" to one of your requests for admission,
here you go.
Courtesy of Justice Perluss.