I think you probably should have been on the Photoshop forum but I'll answer anyway.
First let's get the terms straight. you san you are creating images, some PSD and Some JPEG sized 8.5 X 11 X 300pix... I think you mean 8.5 X 11 at 300 PPI. This means that the images are 2550 X 3300 pixels. There is no difference in the resolution or sharpest of the PSD vs the JPG providing you don't compress the JPEG to death. The only difference is file size and quality of the pixel information of each individual pixel. At 100% quality setting for a JPEG it would be very hard to distinguish between the pixels of a JPEG and A PSD. To test this open one of your PSD files then place a JPEG of the same image on the top layer of the PSC and set the blend mode to difference. Any pixel that does not turn completely black is a pixel where the information in the JPEG is different than the information in the PSD.
Now lest's talk about the images you want to e-mail. You say they are saved at 3.86 X 5 X 300 pix. Again I think you mean 3.86 X 5 at 300 ppi. This means that the smaller JPEG images are 1158 X 1500 pixels. By todays standards these are awfully small images. There is also one more point. The PPI settings for images you are going to email does not matter at all. The ppt for images you are going to put on a web page does not matter at all. The PPI also makes no difference if the image is going to be used in a video or flash or being displayed on a computer monitor. Only images destined for a printer to be printed on paper or some other media care about the PPI settings. Everything else should be sized by the pixel dimensions.
To prove my point download these two images and open them in Photoshop and check the PPI setting. The place them in something going to a printer like a word doc or in Illustrator set up for a print document and check out the size.
My iPhone shoots 2448 X 3264 pixels and I email them all the time. You can see almost every pixel on a standard HD monitor. Sending your 1100 pixel wide images to an HD monitor would only fill about half the screen.
So here's the long and short of it. Most cameras now days hoot way more than 2500 pixel wide images. Even my Sony point and shoot takes images that are 4000 X 6000 pixels. If you are resizing your original images and reducing the number of pixels you are reducing the resolution of the image no matter what the PPI setting is. You are limiting your ability to manipulate the images again later. I wouldn't do it. Saving for Print at 8.5 X 11 at 300 PPI is probably pretty good but with some of todays high quality printers you may want to increase that to 400 or maybe even higher. As for attaching jpegs to emails or sending them to a computer screen or monitor you want the images at least a wide as the display is in pixels. Many e-mail clients will automatically scale down an attached image to 600 or 1000 pixels wide, but on a modern 4K or even 5K monitor these images would be tiny. I'd design my workflow with the final destination in mind and make sure that I don't downsize any camera originals. At least that's my 2¢.
Thank you for the long and detailed answer, it filled all the gaps that I had doubts about. Now, a least when I save my JPG pictures, I will save them as (max) 100% but I think that is all I can do to keep emailed pictures viewable... without scrolling. I tried everything else.
This is a follow-up on emailed picture sizes. You right, you right! All these years I never noticed… Attached high and now res pictures are all show up as same sizes on the receiving end!!!