If it is to show appreciation for our service members than I am all for it.
I spent the better part of 3 years in DC planning all that Military Pomp you see on TV. The logistics of this type of a large scale parade is a nightmare, and that's just regarding the personnel, the hardware is even worse.
If we want to show appreciation to our service members then don't make them spend their off duty time practicing for a parade like this, not to mention the preparation time to move that type of hardware to DC. They will need to go outside the DC area to get the manpower for a parade like this, the Honor Guard units in DC will not be nearly enough to fill even a single block of the parade. The incoming service members will need to be housed, they will be away from their families, and if this happens on a holiday weekend they lose their normal 4 day weekend. That may sound trivial but these guys hate to miss them, it's a great time to spend with family.
Now consider if they do this over the 4th of July, have you been in DC for the 4th, hot and humid is an understatement. While the parade may last 2 hours, these service members will be out there hours early just standing around in the heat in full gear, Believe me, appreciation is not what they will be feeling.
You want to show appreciation for our service members, have a civilian parade outside a military base, throw a big Military Appreciation Day at a base and invite the service members and their families. Don't take away their off duty time to prepare for a parade, make them stand around all day in 100 degree heat and then march down the street so they can be a photo op. There are professional Honor Guard units in DC that are paid to do just that, it's what they do and they do it well.
Military units get the chance to march in local parades, they get the applause from the crowds showing their appreciation, but trust me, very few actually enjoy having to do those parades.
I'm not trying to make a blanket statement that everyone hates doing these parade, just that given the choice most would take a pass.