That being said, all the input here has kind of got me excited to look at some existing "non solo play" adventures and either modify them for my own uses or maybe take some time and create my own adventures.
I'm thinking of busting out the DM Guide (I don't have any of the Essentials line, just the original PHB, DMG, MM that I bought when 4e came out years ago) and looking up how I might be able to modify some of the adventures "down" to a 1-2 player style adventure. Thoughts?
Modifying Encounters: To follow up on Zaran's comment, I'm looking at pages 56-57 of the DMG. Your encounter budget = # of PCs/NPCs in party * XP value of monsters of the encounter's level. A typical encounter ends up with 1 standard monster for each party member, or you "trade in" 1 standard monster for 4 minions (which are the same as the standard monster but with only 1 hp).
You choose the encounter level, where encounters of standard difficulty are +0 or +1 con. You probably want to stick with this difficulty level, or perhaps lower (-3 to -1 level) or higher (if the PC has a good build for example) to mix things up.
Dungeon Delves: If you're up for some light preparation, there is a 4e book called Dungeon Delves. A delve is a short adventure with only 3 encounters in a "dungeon crawl" format (its in a tower, a temple or actual mini-dungeon).
You can start with wrapping a story around a delve or using the one already provided. For example, Delve 1 is Coppernight Hold, a mine delve. It has a short paragraph on background, or you can create your own, say tying the PC to it.
Each delve has 3 encounters, so you can keep as is or modify them with less/more/different monsters or add traps/terrain. You can add more story elements to each encounter like adding a slave pen in one, giving the PC a choice of freeing them or not.
Think an adventure with only 3 encounters is too short? Well, you can string two delves together, say starting with a temple delve that has a secret door to a dungeon delve. Or you could break up the 3 encounters with skill challenges. For example, take a simple, 3-room dungeon delve. Kill monsters in room 1, go to room 2 then 3. Pretty boring right?
Well, add a skill challenge after the room 1. Say there is an underground river that has to be crossed (and you create a skill challenge to that effect). Once the PCs overcome that, they reach room 2. After room 2, they have to cross a massive chasm where stirges attack them (skill challenge #2 or perhaps a SC and combat). After that, they finally reach room 3.
That's plenty of encounters for a 3-4 hour session.
Hope that helps. Good luck and welcome back to gaming!
EDIT: Making Your Own Adventures: If the Reply If You Love 4e thread (
http://www.enworld.org/forum/d-d-4t...315671-reply-if-you-love-d-d-4th-edition.html) is any indication,
4e makes it incredibly easy to create or customize your own adventures. Now, I subscribe to DDi and use MB extensively , since I customize or create from scratch each and every encounter. But I am blown away with how easy it is. I'm an experienced GM so I tend to know what I want out of an encounter. I modify or create new monsters all the time, so I do that through MB and import the text to Word/Excel. I'd estimate it takes an hour - tops - to finish all the crunch aspects for an 8-hour adventure. Amazing, really.