nilofera - If you have planned for good structural bones with your architect already, think of upgrades that will enhance how you use / live in the space or that will add quality of life when you are living there. The options are almost endless.
I would get the highest quality windows you can
Foundation? Think about going with 9' forms - makes a huge difference in how a basement feels.
electrical - upgrade to an extra 100amp sub-panel for a future generator or even up to 2 - 200 amp panels
pre-wire for outdoor lighting, extra lamp posts down the driveway, in ceiling speakers or perhaps a hot tub in the back yard.
I'm planning on timers in lieu of switches in kids bedrooms, bathroom and hall
Storage! Sneak it in everywhere you can. Closets, built-in, cabinets.
Hope this helps!
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Different idea for beam
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