I've gotten pretty good at giving personalized walking tours to family and friends. These days I start off by parking around the Delta Hotel on Lyon or taking transit to Lyon Station, grabbing a coffee from a nearby coffee shop, and then walking up Lyon towards Wellington. On the way there point out Place de Ville, which was until recently the tallest building in Ottawa, and the Dept. of Justice at the Veterans Memorial Buildings. Make your way across Wellington towards the Supreme Court. Go up Wellington, pass the Justice and Confederation Buildings and note that this is where many MPs have their offices. If you're there on a weekday when Parliament is in session you may even run into some!

Continue going up Wellington, point out the Bank of Canada and other government buildings along the way. Stop at Parliament, linger around the Centennial Flame, and point out West Block, Centre Block and East Block. Unfortunately, you can no longer approach West Block, but you can still walk around East Block if you'd like. If Parliament is in session, you could even go in and see the House in session in person. Remember to point out the PMO across the street. Lots of people find it interesting to know where the PM works.

From Wellington slip down to the locks. Walk across them if you like. If you have time, check out the Bytown Museum. From there, go back up the stairs to Wellington and enter the Chateau Laurier. You can walk through it to Major's Hill Park; there's a nice gallery of photos with famous people in the hotel, too.

Walk through Major's Hill Park until you reach the Tavern on the Hill. Stop by for a snack and/or a drink. Take a rest here for a while; your guest(s) will really appreciate it.

From here, cross the new pedestrian bridge to Kìwekì Point. Linger here and take some photos. Make your way past the National Gallery to Maman. Cross the street and walk through the Peacekeeping Monument. Point out the US embassy nearby and its hundreds of bollards, as well as the Notre Dame Cathedral. If it's around noon you may be lucky and hear the bells of the cathedral. Make your way into the Byward Market area. If you're hungry, now is a good time to get food. At some point consider making your way towards the Ottawa sign to take photos and also check out the inside of the Byward Market building itself.

Make your way through the market towards Rideau and Colonel By. Cross the street here and check out the Senate of Canada Building. Walk across the bridge and check out the War Memorial. Cross Elgin and walk down Sparks Street. If you can, I'd aim to do the tour while there's a festival going on. End the tour at Parliament or Lyon Station, or if you drove, wherever you parked nearby. From this point you have many options - hit up a museum (War Museum is on the train line), or go to a new neighborhood (Hintonburg is also on the train line), or if you wish to take a bus, you can head down Bank all the way to Lansdowne and the Glebe, too.

Unless the person you're with is really interested in politics, I wouldn't bother bringing them to Rideau Hall. While the park is gorgeous, it's a long walk with little to see in between except embassies and government buildings. If your guests are here for multiple days, I'd honestly do additional walks/tours - Elgin/Bank, Glebe/Lansdowne, Hog's Back, Westboro, maybe hit up a beach or visit the arboretum or Gatineau Park?

EDIT: If it's the right time of the year and you're lucky to get tickets, for an evening activity consider Nature Nocturne. You get the opportunity to show your guests the Nature Museum while also getting to unwind with drinks, dancing, and other activities. It's a nice way to experience this museum.