I know the hotels topic has been discussed (and I read it carefully), but I would appreciate a quick advice if anyone can share their experiences/views.

Last minute trip to Tokyo next weekend, two parents and two kids (2 and 8). My favorite FS Marunoucchi is not available and, in general, looks like a heavily booked weekend. Can get a Junior or possibly corner suite at the ANA Intercontinental or a Premier Grand room at Mandarin Oriental through AX Plat FHR, 1 one night free deal (or if I really wanted to splurge, can get a suite at MO). Given the kids, which hotel would you recommend? Has anyone stayed at Jr. Suites at IC? Big enough or is it just a big(ger) room? And in general, in terms of amenities and comfort. Don't want to though the money away just for the luxury name, so very open to other options as well.

Thanks for any suggestions/thoughts! Need to act fast.