PA28 - a good way to stay current after your ME/IR is to practice on a cheap(ish) simulator, like an FNPT II, doing SIDs and STARs, shooting ILS approaches, going missed into the hold, etc. That will provide much better value for money than renting a twin, or even flying a Warrior IFR. The practice will also prove useful if and when you get a sim assessment with an airline (even on a different sim).
This (monthly) practice can be arranged with a number of FTOs.
Cheers
IAF_22: my (JAA) licence mentions IR SPA/ME, or Instrument Rating - Single Pilot Aeroplane/Multi-Engine. Check the Rating Revalidation Page of your licence.