Staying in midtown? First and most important rule. GET OUT OF MIDTOWN! Midtown is mostly tourist stuff anyway. Sure, you have to photographer the Chrysler building and the Empire State Building so get it out of your system. The other thing that is kind of in midtown is Grand Central Station. Spend a few hours in Grand Central Station . Good place for people & architectural photography. Save this if it's raining and you need to be inside. Now, lets get you out and about. Take the F train to York Street in Brooklyn (buy yourself a 3 day unlimited card, subways is the best way to get around, safe & fast). Walk through DUMBO to Brooklyn Bridge Park (this is a short walk but gets you under 2 bridges and the best views of Manhattan. Continue in the park under the Brooklyn Bridge to the Squibb Park rope bridge. go past the bridge and take some photos of the skyline with the burnt out pier pilings. Now up the Squibb Park bridge to the Brooklyn Heights Promenade (think Moonstruck). You then have the choice to walk through Brownstone Brooklyn or walk over the Brooklyn Bridge to lower Manhattan. This should fill up a day and a memory card or 2.
Another day you can catch a subway to the Lower East Side (F train again to Essex Street) walk around the Lower East Side and then walk over the Williamsburg Bridge to hipster Brooklyn in Williamsburg. Take the L train back to the end (8th Avenue and if you have anything left in your legs you can walk visit the Chelsea Markets and walk up the HighLine Park. You might also want to take the tram to Roosevelt Island and see Freedom Park. Great views of Manhattan here. As to Museums the Museum of Modern Art can be hit or miss and is usually impossibly crowded. There is plenty to see and photograph at the Metropolitan Museum of Art. Here is my best tip. It is open until 9PM on Friday and Saturday. The crowds really thin out after 5PM. Go at 5 stay until 9. If it's nice out it is safe to walk around the Central Park reservoir at night. Other ideas are the Brooklyn Botanical Gardens and one of my favorites is Green Wood Cemetery. Not hard to get too and definitely something special that the tourists don't see. Once again GET OUT OF MIDTOWN! Midtown is for tourists. You can do well with just the 24-105. Thats is what I use about 95% of the time. The wide angle will be useful too. If you don't have a Black Rapid or something similar you might want to consider it. Takes a big load off your neck and will add hours to your shooting day. BTW Grand Central Station and I think the museums frown on tripods. Best time and place for a tripod is Brooklyn Bridge Park at night. Welcome and have fun
Been their once and that right there really really makes me want to go back, have to admit we did get caught in the 'tourist trap' some what, but it's a very enjoyable trap to get caught in. Difficult to balance the must sees with further afield attractions especially with a family addicted to shopping!