Slash the price and set an offer date for two weeks away. Hold open houses bithe weekends and one evening each week so all the buyers in the market come and see everything you've mentioned. Have your agent tell all interested parties that you are going to sell the property to someone and you will not be countering anyone so if they are intersted in buying to put their best offer forward. The buyers will compete with each other to buy your house and the offers you get will set the market value, whatever that is.
Markets sometimes need to be created. It is human nature to want what everyone else wants so you need to create the buzz around the goods you want to sell.
There are a couple of facts that you should be aware.
First, homes that sell in the first 30 days sell closest to asking price. The longer a home sits on the market, the greater the gap between asking and sales price. Right now, in my MLS, homes at 120 Days on Market (DOM) are averaging 93.6% of asking...that would be AFTER a couple of price reductions.
Second, if a home is on the market and not receiving showings, that is a sign it is over priced. The buyer first sees the home they purchase with a Realtor 90% of the time, so Realtors know value and don't waste their time , or their buyers, showing over-priced property.
Third, ask your Realtor for a CMA, which will include all properly that has sold since your property hit the market. The fact is that you do not want your home to sell in average market time. If the average is 200 DOM, you now realize that to get highest price you need to sell in UNDER 30 DOM. That means that the true market is in two parts. One part is selling under 30 days, 20-25%, the remainder are overpriced and are selling in 100-150 DOM.
Once you have an offer, you should be able to negotiate "possession time", or exactly when your buyers move in. Sometimes a "rent back" can be negotiated to help you only have to move once.
As for investors, they are not likely to be interested in a home that is priced at market value. It's the old cliche--buy low and sell high. In addition to this, real estate investors also need to have a positive cash flow that market values just do not afford them.